I shoot on the house range here at our little ranch, but back when I loaded rounds to take to the range for group testing, I loaded 12 rounds of each powder charge. Shoot 10 (two 5 round groups) clean bore lightly, shoot 2 foulers, go to next load.
These days I might do it a bit differently and not clean so often - but that would depend a lot on the rifle and how it tends to foul.
But at the house range, where the bench is 50 feet from the reloading bench, I'll load and shoot 3 round groups. If the group looks bad, I'm on to the next one. If the group looks good, I'll make it a 5 round group. Take notes and go to the next load. When I think I have the 'load', I'll shoot it a bit to convince myself it's the right one. And the next day I'll try a cold bore shot and group to see if I've got what I need. As for bore cleaning, it's a bit irregular now. I don't clean as much, since I don't think it's so necessary, except for the 220 Swift, which fouls pretty fast.