Everything on the machine is modular and repairs are quite simple. Even if you find you are doing maintenance more frequently (not my experience as an owner and developer - much heavier use than a typical homeowner), repairs are much faster. I've built games using the Lexy, Heist, and CCR playfield modules. Thousands of games across each both for my own games and the base games.
Flipper needs tweaking? Alignment is automatic, but sliding the flipper/sling assembly out gives you easy access front and back to coils, etc. Roll pins are held in place with a sturdy collar and can be removed without tools to change bats if needed. Makes changing a flipper bat/linkage a 1min process.
Pop bumper switch need adjusting? Pull the module out, flip it upside down, tweak, reinstall. Maybe 3 minutes (you have to push the balls back into the trough that are staged for launch before reinstalling the module).
The connections and diagnostics are also easy to review and understand, and allow for more in-depth testing of some of the more complex mechanisms.
The complete playfield assembly is heavy, but it can be placed in multiple positions to aid in troubleshooting, if desired.
I test the heck out of all my games with regard to coin/free play and various settings. Never an issue there.
I would also suggest reaching out to Gerry as he will be able to discuss common issues. They have a support site with very clear instructions for adjusting complex mechanisms (like third flipper assembly, or crane in Heist).
I work on a lot of games, including labor-intensive games like bingos. I find the P3 to be the easiest modern game to maintain out of any I've worked on.
Hope to put my P3 on route at some point to see how it earns, and rotate in a different game every few weeks.
But I keep making games for others to enjoy instead. I'm not an op, so just my 2c as a customer and 3rd party developer.