In my small shop, the wall studs are on 20" centers. There are a lot of them for such a small area. I put a double outlet box on every stud at 42" from the floor. I have outlets behind stuff that won't get used at all unless I move what's in front of them. But, they are there if and when I need them. Over my workbench, I have even plugged in six way outlets in order to have enough for all the stuff that I have plugged in. I have a computer monitor and the actual box, that's two right there. I have my Fein plugged in, a small air compressor plugged in, a soldering station, drill press, Dewalt saw, light/magnifier, fan, radio and a 6 outlet strip that powers my two battery charging bases for my drills. I could go on and on. The point I am making, you can't have enough outlets. I put them all on a dedicated 20 amp circuit. My lights are all on a dedicated 15 amp circuit. I also put 2 double boxes outdoors for when I am working on my driveway. If I had a shop the size of yours, I can't imagine how many boxes I'd have. A huge amount though.