Hey Colin,
NI recommends against doing many self-cals just because of the "general" user case. "General" users of our DMMs might not understand about calibration and may not have the board in "ideal" conditions for each self-cal...ultimately doing more harm (i.e. calibrating in bad environmental conditions) than good. As long as you keep it in the correct temperature range, you can schedule the self-cal process at long intervals from the last. "Too frequent self-cal" is not a "problem". It's just somewhat of a guideline to follow for most DMM users.
Sincerely,
Gavin Goodrich
Applications Engineer
National Instruments
