I've found that it's pretty much split between if I have a landlord that's just a guy with a few houses vs a property management company. When I lived in a complex (cheaper than my current rent by a mile because it was in NC), maintenance would be over in a matter of hours. When I've had a single guy, it's often days (unless it's a truly urgent issue).

I'm under a guy that just manages 20 or so doors now and he's a good dude, but I have to wait a longer time, generally, like when my heat wasn't working at the beginning of the winter and his plumber had the flu. Luckily it wasn't bad weather yet, but I definitely felt the potential for strain.