I think 3x a week is a bit much. Your risking a lot of scar tissue IMO. I'd rotate delts and quads into the mix. I've never done more then 3cc's in a glute either. Delts. the max has been 2.
I can do 5cc's in any of my injections spots: glutes, quads, delts, and bi's. I rotate through them all and I have never had a problem with scar tissue or absess'. Unless you are a really small guy, you shouldn't have a problem in my opinion.