"How many" shops you can do really depends on the type of shop. There is a huge difference between doing a dozen unrevealed gas station shops and doing a dozen car dealerships or written apartment shops.
While planning a big day of shopping, be sure you:
* Plan your route starting at the furthest location from home, if possible. (If your timing is off and you miss a shop, you want it to be the visit just down the street, not the one 50 miles away.)
* Estimate how long you are going to spend inside each location.
* Map the driving times between each location - be sure to account for potential traffic delays.
* Build in extra time - something will go sideways if you are doing 10 shops.
* Make sure you will have time to do all your reports after the shops.
Hard work builds character and homework is good for your soul.