Because the events are logged as they are received and one at a time the monitor frequently fails due to the following error when events are generated at a high rate.
botocore.exceptions.ClientError: An error occurred (ThrottlingException) when calling the PutLogEvents operation (reached max retries: 4): Rate exceeded
This results in loss of events recorded in the log stream.
The throttling could be alleviated by maintaining a queue per log stream and batching calls to PutLogEvents.