It is most likely going to be same area and not the same spot. When I am cycling and have a good volume in my syringes, I just rotate between left and right glute and change the spot around. You will be able to tell if you are getting scar tissue or not, the pin will go in harder.
I usually pin 3 ml. At a time and give a site a week ... i think those doing site injections prove even a smaller muscle can take far more frequency than that
7 days for me. If there's still any mark left from my previous injection I'll move it a couple cm in another direction to make sure I'm not hitting the exact same spot. When I am using long esters and only doing 2 shots per week I honestly just rotate glutes. When I am using shorter esters that's when I'll start to get more creative with injection sites.
I would think this depends on the amount being injected and the size of the muscle. 3cc in a bicep will do more damage than 1cc in a glute, so you would need more recovery from the former than the latter. How much are you injecting and where?
I used to split all my gear into 3 pins per week no matter what i was doing. I pinned MWF to keep the levels more stable. I would pin the same spot about every 7 does or so.
I rotate to as many muscle groups as possible in order to give them maximum rest time. For me it works out to 10 days minimum but the longer the better.
Call me paranoid about the build up of scar tissue, but at least 7 days for me. I also use several different muscles to rotate with, but NEVER again the calf :-0! I heard of it, read up on it, tried it, and paid the price with pain lol