As a maintenance crewman for the last 36 years I have to partially agree with 212man. When you do an overhaul or perform almost any maintenance that requires disassembly of parts (which I think is the definition of maintenance), you run the risk of incurring some damage that was not there before your endeavor. We have all cut an o ring while reassembling something and fortunately we usually find the seep/leak before it goes back in service. Sometimes it takes a while to show up. The chances of catastrophic failure are slim but it can happen ( S92 oil filter studs not withstanding). I think if people get complacent because they do something every day the likelihood increases but filters and O rings should never fall into that category if proper procedures are followed, even if it means replacing cheap o rings every day and performing an extra run-up to leak check. Geez, do you check your landing light on pre-flight or do you think that if you turn it on an extra time that might be the last time it works before it fails and you would have been better off not checking it because it would work when you actually needed it? I think I'll stay in bed today......