diff --git a/src/weathergen/train/lr_scheduler.py b/src/weathergen/train/lr_scheduler.py
index e85cd1abf..9c8185fc2 100644
--- a/src/weathergen/train/lr_scheduler.py
+++ b/src/weathergen/train/lr_scheduler.py
@@ -53,9 +53,9 @@ def __init__(
             logger.debug(f"steps_decay={self.n_steps_decay} lr_steps={lr_steps}")
         # ensure that steps_decay has a reasonable value
         if self.n_steps_decay < int(0.2 * lr_steps):
-            self.n_steps_warmup = int(0.1 * lr_steps)
-            self.n_steps_cooldown = int(0.05 * lr_steps)
-            self.n_steps_decay = lr_steps - self.n_steps_warmup - self.n_steps_cooldown
+            self.n_steps_warmup = max(2, int(0.1 * lr_steps))
+            self.n_steps_cooldown = max(1, int(0.05 * lr_steps))
+            self.n_steps_decay = max(1, lr_steps - self.n_steps_warmup - self.n_steps_cooldown)
             s = (
                 "cf.lr_steps_warmup and cf.lr_steps_cooldown",
                 f" were larger than cf.lr_steps={lr_steps}",
diff --git a/src/weathergen/train/trainer.py b/src/weathergen/train/trainer.py
index f396e611c..a31dd57a7 100644
--- a/src/weathergen/train/trainer.py
+++ b/src/weathergen/train/trainer.py
@@ -86,6 +86,7 @@ def __init__(self, train_logging: Config):
         self.batch_size_test_per_gpu = -1
         self.collapse_monitor: CollapseMonitor | None = None
         self.perf_tracker: ThroughputTracker | NullThroughputTracker = NullThroughputTracker()
+        self.t_training_start: float = 0
 
     def get_batch_size_total(self, batch_size_per_gpu) -> int:
         """
@@ -321,7 +322,7 @@ def run(self, cf, devices, run_id_contd=None, mini_epoch_contd=None):
         # aiming for beta1 = 0.9 at one node, ie kappa=B=4
         beta1 = max(0.5, 1.0 - kappa * (1.0 - self.training_cfg.optimizer.adamw.beta1))
         # aiming for beta2 = 0.95 at one node, ie B=4
-        beta2 = 1.0 - kappa * (1.0 - self.training_cfg.optimizer.adamw.beta2)
+        beta2 = max(0.9, 1.0 - kappa * (1.0 - self.training_cfg.optimizer.adamw.beta2))
         eps = self.training_cfg.optimizer.adamw.get("eps", 2e-08) / np.sqrt(kappa)
 
         self.optimizer = torch.optim.AdamW(
@@ -361,7 +362,7 @@ def run(self, cf, devices, run_id_contd=None, mini_epoch_contd=None):
             mini_epoch_base = int(self.cf.general.istep / len(self.data_loader))
         else:
             len_per_rank = (
-                len(self.dataset) // (self.world_size_original * self.batch_size_per_gpu)
+                max(1, len(self.dataset) // (self.world_size_original * self.batch_size_per_gpu))
             ) * self.batch_size_per_gpu
             mini_epoch_base = int(
                 self.cf.general.istep
@@ -379,6 +380,7 @@ def run(self, cf, devices, run_id_contd=None, mini_epoch_contd=None):
         self.validate_before_training()
 
         # training loop
+        self.t_training_start = time.time()
 
         for mini_epoch in range(mini_epoch_base, self.training_cfg.num_mini_epochs):
             if is_root():
@@ -747,6 +749,7 @@ def _log(self, stage: Stage):
                 self.train_logger.add_logs(stage, samples, losses_all, stddev_all)
 
             elif self.cf.general.istep >= 0:
+                elapsed_time = time.time() - self.t_training_start
                 self.train_logger.add_logs(
                     stage,
                     samples,
@@ -754,6 +757,7 @@ def _log(self, stage: Stage):
                     stddev_all,
                     avg_loss=avg_loss,
                     lr=self.lr_scheduler.get_lr(),
+                    elapsed_training_time_seconds=elapsed_time,
                 )
 
         loss_calculator.loss_hist = []
diff --git a/src/weathergen/utils/plot_training.py b/src/weathergen/utils/plot_training.py
index 5678cbbc2..059ea57bf 100644
--- a/src/weathergen/utils/plot_training.py
+++ b/src/weathergen/utils/plot_training.py
@@ -311,6 +311,7 @@ def plot_loss_avg(
     runs_data,
     runs_active,
     stage=TRAIN,
+    x_axis: str = "samples",
     x_scale_log=False,
     legend_outside: bool = False,
     legend_font_size: str = "x-small",
@@ -322,10 +323,14 @@ def plot_loss_avg(
 
     _fig = plt.figure(figsize=(10, 7), dpi=PLOT_DPI_VALUE)
 
+    # x-axis label: "elapsed_training_time" -> "elapsed training time [s]", else "step"
+    x_label = "elapsed training time [s]" if "elapsed_training_time" in x_axis else "step"
+
     legend_str = []
     for i_run, (run_id, run_data) in enumerate(zip(runs_ids, runs_data, strict=False)):
         run_data_stage = run_data.train if stage == TRAIN else run_data.val
-        x_vals = np.array(run_data_stage["num_samples"])
+        x_col = next(filter(lambda c: x_axis in c, run_data_stage.columns))
+        x_vals = np.array(run_data_stage[x_col])
         y_vals = np.array(run_data_stage["loss_avg_mean"])
 
         mask = np.logical_and(~np.isnan(x_vals), ~np.isnan(y_vals))
@@ -347,7 +352,7 @@ def plot_loss_avg(
         plt.xscale("log")
     plt.title("average loss")
     plt.ylabel("loss")
-    plt.xlabel("step")
+    plt.xlabel(x_label)
     plt.tight_layout()
     _add_legend(
         legend_str,
@@ -379,10 +384,9 @@ def plot_loss_per_stream(
     channels: list[str],
     forecast_steps: list[int],
     x_axis: str = "samples",
-    x_type: str = "step",
+    x_scale_log: bool = False,
     x_lim: list[float] | None = None,
     y_lim: list[float] | None = None,
-    x_scale_log: bool = False,
     legend_outside: bool = False,
     legend_font_size: str = "x-small",
     legend_num_columns: int = 3,
@@ -408,9 +412,7 @@ def plot_loss_per_stream(
     errs : list
         list of errors to plot (e.g. mse, stddev)
     x_axis : str
-        x-axis strings used in the column names (options: "samples", "dtime")
-    x_type : str
-        x-axis type (options: "step", "reltime")
+        x-axis column name used for the x-axis (options: "samples", "elapsed_training_time")
     x_scale_log : bool
         whether to use log scale for x-axis
     """
@@ -525,7 +527,13 @@ def plot_loss_per_stream(
                 title_loss = ".".join(title_col.split(".")[:-1])
                 plt.title(title_loss + " (" + ", ".join(modes) + ")")
                 plt.ylabel(err)
-                plt.xlabel(x_axis if x_type == "step" else "rel. time [h]")
+                # x-axis label: "elapsed_training_time" -> friendly name, else use column as-is
+                x_label = (
+                    "elapsed training time [s]"
+                    if "elapsed_training_time" in x_axis
+                    else x_axis
+                )
+                plt.xlabel(x_label)
                 plt.tight_layout()
                 _add_legend(
                     legend_str,
@@ -596,7 +604,7 @@ def plot_loss_per_run(
     errs : list
         list of errors to plot (e.g. mse, stddev)
     x_axis : str
-        x-axis strings used in the column names (options: "samples", "dtime")
+        x-axis column name used for the x-axis (options: "samples", "elapsed_training_time")
     x_scale_log : bool
         whether to use log scale for x-axis
     """
@@ -666,7 +674,10 @@ def plot_loss_per_run(
         plt.xscale("log")
     plt.grid(True, which="both", ls="-")
     plt.ylabel("loss")
-    plt.xlabel("samples")
+    x_label = (
+        "elapsed training time [s]" if "elapsed_training_time" in x_axis else x_axis
+    )
+    plt.xlabel(x_label)
     plt.tight_layout()
     _add_legend(
         legend_str,
@@ -794,13 +805,13 @@ def plot_train(args=None):
         help="x-lim for per-stream plots",
     )
     parser.add_argument(
-        "--x_type",
+        "--x-axis",
         "-x",
-        dest="x_type",
-        default="step",
+        dest="x_axis",
+        default="samples",
         type=str,
-        choices=["step", "reltime"],
-        help="Type of x-axis used in plots. Options: 'step' or 'reltime'",
+        choices=["samples", "elapsed_training_time"],
+        help="X-axis column for plots: 'samples' (default) or 'elapsed_training_time'",
     )
     parser.add_argument(
         "--log-x",
@@ -862,9 +873,7 @@ def plot_train(args=None):
     model_base_dir = Path(args.model_base_dir) if args.model_base_dir else None
     out_dir = Path(args.output_dir)
     streams = list(args.streams)
-    x_types_valid = ["step"]  # TODO: add "reltime" support when fix available
-    if args.x_type not in x_types_valid:
-        raise ValueError(f"x_type must be one of {x_types_valid}, but got {args.x_type}")
+    x_axis = args.x_axis
 
     # Post-processing default logic for config from YAML-file
     if args.fd is None and args.fy is None:
@@ -924,6 +933,7 @@ def plot_train(args=None):
         runs_data,
         runs_active,
         plot_dir=out_dir,
+        x_axis=x_axis,
         legend_outside=args.legend_outside,
         legend_font_size=args.legend_font_size,
         legend_num_columns=args.legend_num_columns,
@@ -937,6 +947,7 @@ def plot_train(args=None):
         runs_data,
         runs_active,
         stage=TRAIN,
+        x_axis=x_axis,
         legend_outside=args.legend_outside,
         legend_font_size=args.legend_font_size,
         legend_num_columns=args.legend_num_columns,
@@ -953,7 +964,7 @@ def plot_train(args=None):
         errs=args.metrics,
         channels=args.channels,
         forecast_steps=args.forecast_steps,
-        x_type=args.x_type,
+        x_axis=x_axis,
         x_scale_log=x_scale_log,
         x_lim=args.per_stream_x_lim,
         y_lim=args.per_stream_y_lim,
@@ -972,7 +983,7 @@ def plot_train(args=None):
         errs=args.metrics,
         channels=args.channels,
         forecast_steps=args.forecast_steps,
-        x_type=args.x_type,
+        x_axis=x_axis,
         x_scale_log=x_scale_log,
         x_lim=args.per_stream_x_lim,
         y_lim=args.per_stream_y_lim,
@@ -991,7 +1002,7 @@ def plot_train(args=None):
         errs=args.metrics,
         channels=args.channels,
         forecast_steps=args.forecast_steps,
-        x_type=args.x_type,
+        x_axis=x_axis,
         x_scale_log=x_scale_log,
         x_lim=args.per_stream_x_lim,
         y_lim=args.per_stream_y_lim,
diff --git a/src/weathergen/utils/train_logger.py b/src/weathergen/utils/train_logger.py
index 53e4e551f..d7501a1cd 100644
--- a/src/weathergen/utils/train_logger.py
+++ b/src/weathergen/utils/train_logger.py
@@ -101,9 +101,10 @@ def add_logs(
         stddev_all: dict,
         avg_loss: list[float] = None,
         lr: float = None,
+        elapsed_training_time_seconds: float | None = None,
     ) -> None:
         """
-        Log training or validation data
+        Log training or validation data.
         """
         metrics: dict[str, float] = dict(num_samples=samples)
 
@@ -112,6 +113,13 @@ def add_logs(
             metrics["loss_avg_mean"] = val
             metrics["learning_rate"] = lr
             metrics["num_samples"] = int(samples)
+            if elapsed_training_time_seconds is not None:
+                metrics["elapsed_training_time_seconds"] = elapsed_training_time_seconds
+                metrics["average_samples_per_second"] = (
+                    samples / elapsed_training_time_seconds
+                    if elapsed_training_time_seconds > 0
+                    else 0
+                )
 
         for key, value in losses_all.items():
             val = np.nan if np.isnan(value).all() else np.nanmean(value)