You can get blood from pinning anywhere. You are pinning flesh. I'm off TRT now for a while but I have been doing delts the majority of the time. It's the easiest for me and least painful. I do it in bed with a bunch of pillows behind my back, and one big one under the arm I'm pinning. This keeps my arm relaxed and rotates the delt toward me so I get a better angle. The shots typically don't hurt or I get a slight pinch here and there. Usually that pinch is just near the surface of the skin; once you get past that, it's smooth sailing/pinning. Glutes were always tough for me and my hands shake too much. Quads are either the most painless or the most painful, and when you get pip in quads, lord have mercy.