Do solo founders really need documentation or is it a waste of time?

I always thought documenting things was useless if you’re building alone

But after stepping away from my app for a couple weeks I came back and had no idea why I set up parts of the product the way I did.

Lately I started taking 30 seconds to write down the reasoning behind tricky decisions. It already saved me a bunch of headache this week.

Curious how other solo builders handle this do you bother writing stuff down or just rely on your commit history?