I have always loved composing square pictures...much preferred over 35mm. I have never tried 4x5.
I never get my hopes up when shooting---I will never be a talented photographer, it's just something I like doing. But in general, the more time I spend composing, or just observing, the more confident I am the shot will come out. Therefore, I have a much, much higher success rate with MF than I do firing off my Nikon N80.
I scan everything I shoot these days. It helps me figure out where shots went right/wrong, and gives me a better idea how to prevent failures the next time around.