The dude who wrote Anabolic Pharmacology (which by the way is the worst book about gear I've ever seen IMO) and I got in a fight over on Anabolic Minds (oooo yea I said it...) about where certain things get absorbed faster and the best and he brought up some bs study that he probably got off of google or something saying that the delt absorbs faster than glutes or the other way around. I can't remember cuz I don't really respect that guy in the least and don't care for what he says.
But all in all you can pin wherever you want really (excluding certain areas of course just out of pure common sense) be it chest, bi's, tri's, vastus medialis, vastus lateralis, glutes, lats, etc. It's all personal preference. But typically people go for the easiest and most fleshy parts of the body... i.e. the legs, tush, and delts. Zomb used to pin chest a lot

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