I've never loaded 50 at a time for testing, I usually only load 7 to 10 and use a rest. By the time I shoot them ,I know how good they group and if they cycle the gun or are dirty ect...You could waste a lot of money and/or time if they don't shoot very good,then you either have to pull them or just blast them off just to get rid of them, not really gaining anything.
I've tried/have quite a few different powders and its surprizing how many times I load up the same bullet over three or four powders and two will group just "ok", one is bad, and the fourth shoots a great group and seems perfect. If I loaded 50 of each, I would have a heck of a pile of worthless rounds to deal with. The "ok" ones I may tweek a bit and retry,but only another 7 to 10.