I used to shoot 3-4 times a day(AAS-IM, Slin-SQ, HGH-IM). Scar tissue isn't an issue unless you are injecting very high volumes of gear. Plus you are using Slin pins so you are fine. I have easily injected my delts thousands of times with AAS and GH, almost no scar tissue at all. The only time i had build up was when i was shooting 3cc into my delts every week. The build up faded after a few months of not shooting delts.
Pin your heart out bro and GROW!