But, it's like we are in different realms - when I work with people i have to purge them of the "these don't exist" and flush them out and start anew.

The p.a. flush issue is negligible (takes 10 mins if you plumb it with foresight).

GFCIs tend to be deeper than regular receptacles; check in the store if the GFCI you are buying will fit flush into the Wiremold box. 

You will have to install a board between the case work flush with the plywood.

If you're flush with cash, I have several I can recommend, but it sounds like you your initial research and learning can be done online.

I don’t care if they’re watching Oprah or cooking supper, I’m not flushing income if I don’t have to.

I was invested in multi-family, but like ss much better because it's just steel and concrete...the tenants can't damage it and no one ever calls me at 6am complaining that their child flushed a toy down the toilet like you get in multi-family.

The most likely culprit - every single time - is a toilet that flushes regularly or runs constantly.

I have fourplexes with shared laundry that are using less than 10,000 gallons per month.Once you confirm that, inspect every single unit yourself to determine if toilets are running or constantly flushing.

People who rent will flush things that the system can not handle.