It depends on what I can add to my bread and butter shops. But normally I max out at 12 because I know keeping everything straight will become difficult when it comes to writing reports.
If I lived closer to civilization in regards to driving time I would have no problem taking on 20 shops that are yes/no and require minimum narratives. I live an hour north of San Antonio during the right time of day, but it normally takes 1 1/2 to 2 hours either way if it's during rush hour traffic. That traffic wears me out because of other drivers cutting in and out of lanes and in general being idiots.
Normally, I pick up rural locations and add a city in the mix. It's longer in mileage and a couple of extra hours in driving. It's heaven sent in the sanity situation.
I make my goal every month and normally only work 4 days a month, so I don't mind the long stuff...if things work the right way.
This month and last month, my game plan hasn't been all that and a box of cracker jacks. I thank the heavens for my schedulers who understand...STUFF HAPPENS!
Live your life in such a way that when your feet hit the floor in the morning; the devil shudders...And yells OH #%*+! SHE'S AWAKE!