Often times, while painting a watercolor you are working up close. Getting totally engrossed in what you are doing. Hopefully enjoying the entire process. Every now and then you need to step back from what you are doing. Prop your painting up on a shelf, a ledge, a bookcase and then step back and take a good look at what you're doing. If you have a working mat, place that on your painting to cover up the tape and the mess on your board.
Step back, stand several feet or more away from your painting. Try standing at a distance where one would most likely stand to view the painting. Are those little fiddly spots really all that important? Are you spending too much time in the little details that will not be seen from several feet away. Most people will not be viewing your art from 6 inches away. Perhaps the happy little accident you are fussing to correct isn't really that noticeable and would most likely be better off left alone.
Prop up your painting, step away from it and view your painting as a whole. Do this several times during the painting process and you will end up working more efficiently and you will also be able to check your composition as you go.