If I'm understanding the question correctly you are asking if its okay to pin 3 cc in one spot in one pin. My answer is yes, as long as your body is OK with two, then try three. I'm fine with three even on Delts. Just rotate injection spots so they get some time off. I rotate between Delts and glutes mostly.
I'll be switching, week for glutes, week for delts,
The cycle before this was test 500 + primo 400
I injected in glutes left/right
For 12 W, i had only pain comes and goes, but was fine, injections hurt so i have to live with it.. Lol
Yeah, everybody's different. Got a lot of respect for Rick, he knows his shit, but I'm OK with 3 in delts. You'll know your own body. I'd rotate sites by injections though ie glute/glute/delt. To allow some time between pins. Good luck with your cycle bro!