Averaging multiple buffers also allows you to separate random processes from deterministic processes. For example, small thermal processes can be detected at the beginning of the measurement.
If there is a pause before filling the buffer (for example, 1 minute), then at the beginning of measurements there is some thermal artifact with a duration of 30 seconds on the 10V and 1000V ranges. It is small and within tolerance.
But if you had a stop of the measurement process (waiting for the trigger), then for the best measurements it makes sense to discard the first 30 seconds of measurements.