I agree with everything said, I do spot under a microscope, but "proof" the spotting from a distance.

There are many pleasurable moments when a spot completely disappears as if by magic.

But there are times when a spot I worked on will look incomplete under close inspection, but it disappears nicely at normal viewing distance.

For those spots, that's where I stop. Spending more time on a spot that is already gone makes it come back.