I don't like scheduling to far in advance. A few days is usually my limit. I do make exceptions for bonused shops though, then I'll start adding shops in the area to go with the bonused one.
I like staying relatively free, so that I can jump in the car and go do a highly bonused shop if the opportunity arises.
It could be that I'm just lucky in my area, I can travel 30 miles in any direction and find 5-6 shops to do.
The only things scheduled in advance in my world is my gas station routes, and I have 5 weeks to complete them. That's one of the reasons I like them.