Only once.
Then ........ after two or three days/weeks/or months of trial and error, trouble shooting with indefinite results, trying to find out which unit is falsing, you'll get the point and change it. But .......on second thought, if you can't understand the reason for doing it ahead of time ...... maybe you wont change it then either. Because ...... after all, what are the chances of it ever happening again ........ Right?