Rotating injections sites is blowing my mind

I've been on Zepbound for 7 months now, currently only 10mg. One thing that amazes me, is how different the medication works from week to week, and from injection site to injection site. Rotating between abdomen and thigh has been a game changer for me. But my mind can't quite understand why it matters. The body and this medication are amazing things.

If anyone has a scientific answer to this, I'd love to hear it.