Usually if I need to clear a mat of seaweed from my rudder, and so sometimes in fairly rough water as that is often where the seaweed has been stirred up after a storm (when the swells are running high and I want to go out).
Like anything, practice and you get better at it. While it initially is disconcerting, I have come to look upon it as another way to increase my balance capability. For a real treat (i.e., balance improvement exercises), once you get decent at it, try doing it with your eyes closed for a bit.
For any paddling skill involving balance, I have found that closing my eyes really helps me improve as I am forced to use only my inherent motion senses and not my vision.
Bill L