Cleaned the desk, moved the monitor back a little, and spent the next session convinced I had changed a mouse setting. I had not. Everything just looked slightly different and I was overcorrecting.

Put the monitor back near its old position and felt normal again. Not claiming some universal magic distance. Mostly sharing because I nearly changed every setting I own to solve a furniture problem.

What is the smallest physical change that has thrown you off?

Different chair height. My arm sat differently and I blamed the mouse for an entire evening.

Are we sure some of this is not just having a bad night and wanting a reason?

Could be part of it. I am not presenting a controlled experiment. I just know moving things back helped me stop fiddling.

The useful lesson seems to be “check what you physically changed before adjusting everything else”. That holds even if part of it was expectation.

My keyboard moved far enough that I kept missing one key. It took longer than I want to admit to notice.

Fair enough. I get wary when these threads become exact measurements everyone supposedly needs. Personal setup notes are useful.