One of the most frustrating and time-consuming aspects of doing a repair is chasing down a part while critical equipment is down. Even more frustrating is when you find somebody used the last one this morning for a low-priority purpose. Sure, a replacement will arrive tomorrow, but that critical machine is down now.
Another frustrating time-waster is you’ve got to spend half an hour taking apart a complex assembly, then another hour reassembling it just to do a 5-min. part