The objective of pre-departure checks is to determine that elements subject to short interval failures are good for now. While these checks do not ensure the elements will survive the entire mission, they do significantly increase the likelihood of survival over that time period because they ensure the process of failing is not already a long way down the path. When elements are found to need attention before the start of a mission, attention is recommended and appropriate action taken.
Tip from: Mission Based Reliability: A Practical Guide to Quick and Focused Improvements by Daniel T. Daley