Everyone is different. My favorite spot is quads. No twisting around etc, just relax and poke.

I use the same stop all the time, never even considered swapping maybe i Should some times i carnt walk for 2 days after injecting haha.

I perfer my side deltas then Glutes did not like the Quads. Here is a web site of places to inject.
http://www.spotinjections.com/

You can switch to different parts of the body.
And not punish any.

I rotate between butt, side delts, and pecs. Quads I hate, way more pain for me.

I do my TRT with 30g 1/2" slin pins in pecs, delts and quads, I use 25g 1 1/2" in glutes when blasting

If it ain't broke why fix it? Pick enough injection sites so you have a once a week rotation.

10-14 days is a good time frame

Add delts and glutes to your rotation. This will give your body time to heal as others have posted.

For 2 to 3 pins a week you'll need at least 4 to 6 injection sites. Give each site 7 to 10 days before pinning again.

I personally rotate up to 6 injections sites. Just in case one gets inflamed or something. I noticed if I don't wait long enough I get Knots.