I finally learned to rotate my injection sites properly

I've been trying to improve my insulin injection routine and realized there are a lot of small details I never thought about.

One thing I'm confused about is whether people inject through clothing when they are in a hurry, and how everyone keeps track of rotating injection sites.

For people who have been doing injections for a long time, what habits helped you avoid using the same spots repeatedly? Do you have a system for remembering which areas to use and which ones to rest?

I'm interested in the practical everyday side of injections, not just the basic instructions.