If you're not working your ass off and seeing huge volume and complex cases as a fellow, you are wasting the year. Remember, you're paying a very large sum of money to be there. Get maximum value for your tuition, er, I mean opportunity cost.
I didn't do my fellowship at Cleveland Clinic, but I am a big believer in workhorse, non-supervisory, do-the-goddamn-cases-yourself, cardiac anesthesiology fellowships (as opposed to echo fellowships).