Took me 3 weekends to find out my shower leak was a $4 rubber gasket

So about 2 months ago I noticed a wet spot on the ceiling in my hallway right under the upstairs bathroom. I did the smart thing first and panicked, then I did the dumb thing and tore open the ceiling thinking it was a pipe. Nope, pipes were dry. Then I pulled the toilet because I read online it could be the wax ring. That was a whole Saturday gone, and it was not the wax ring. Weekend two I cut an access hole in the wall behind the shower and sat there with a flashlight every time someone took a shower, which my wife loved. Finally I ran the shower with just the tub spout on and watched water pool right at the base of the handle, and it turned out the gasket behind the cartridge had dried out and cracked. Whole thing cost me $4 at a hardware store on Central, plus about $60 in drywall I destroyed for no reason. Has anyone else gone through a whole tear out only to find the fix was a little rubber ring?