I got up to that number trying to reduce my mortgage payment (and therefore artificially increase my monthly cash flow), The flaw in that it is I will be tying up a large portion of my cash reserves which would be better spent acquiring more investments.House hacking, just through analysis of a few properties I found online, seems like the better option to me as well.

.), holding your tenants accountable for regular maintenance (changing HVAC filters, lawn & yard maintenance, checking their smoke detectors regularly, etc.)  

The 50% number includes everything: maintenance/repairs, taxes, insurance, lawn maintenance, property management, pest control, trash pickup, etc.

You're missing trash and lawn for sure.

I've seen properties, specifically in the bay area, trying to artificially pump up NOI, with things such as trash valet services.

Lawn care? 

Last month they ticketed me for "debris" on the front lawn of one of my properties.  

I use 5% vacancy , 5-8% maintenance  (lawn care is seperate and number depends on condition), 5% capx ( 8% if roof is older).

Lenders set an artificially low opening bid and then bid it up themselves up to some higher amount (sometimes even as high as a full credit bid). 

Soon, the homes with un-mowed lawns begin to stand out.