Improvement Ravine, over at Martin Fowler’s blog, has one of the clearest examples I know of for plateau-breaking in mastery of a skill.
I love reading about things like this - experiencing it, as the example describes, can be a little less joyful, though having experienced it is a wonderful thing (i.e., it’s not fun while you’re taking the step back, but once you’re over the ravine and back on the improvement track, you’re glad to be there).
I think it’s important to realize that we run into plateaus in pretty much everything we do - from technical skills, to losing weight, to being in a relationship. The tricky thing is to be self-aware enough to recognize that you’re on a plateau, and lucky or clever enough to devise a strategy to get through it.