Looking through the help files for the DMM, I read:
You can obtain optimum performance by running self-calibration once per day, but NI recommends once every 90 days or if the temperature has varied >5 ºC since the last self-calibration. Unless the temperature varies >5 ºC from the last self-calibration, NI recommends against running self-calibration more than once per day.
Why are self-calibrations not recommended to be performed more than once per day? Is this something to do with write cycles to on board memory devices on the DMM card?