[Archer6621]

I also don't believe in this claim, or at least in it being a generally applicable thing.

There's a point at which slowing down gives diminishing returns in my experience. I'm a music composer and I had to learn that the hard way. Sometimes my first ideas end up being good enough already, or even better than previous/future ideas that I had iterated a lot on. I also found that working for too long on a piece can potentially make it worse than previous iterations eventually.

[SamPatt]

I find the same with photography. I notice when editing that the first photo of a scene / subject is the best photo much more frequently than chance.

Though it's also true that the last photo is also much more frequent. If I took 20 photos of something, I'd say I use either the first or last photo taken probably 1/3 of the time.