I used to breeze past full wire checks in homes with existing alarm setups, thinking it was a time-saver. My logic was that if the old system worked, the wiring must be good enough. That changed after a nasty job in an 80s condo where the keypad kept losing power randomly. I wasted a whole afternoon tracing a bad splice in a wall that was hidden behind drywall. A simple continuity test at the start would have flagged it immediately. Now I pull out my multimeter and check each run before I connect anything, no exceptions. It adds maybe twenty minutes to the install, but it prevents hours of headache later. I tell my apprentices this story so they don't make the same lazy call I did.