[rick-slo]

You usually do need to play something over and over to discover and overcome all the little gotchas some pieces have.

I vary tempo while working on something, more so on the harder pieces. I like to get a feel for how a piece flows (section by section as needed) ASAP so that I can practice my phrasing while practicing memorization. Also, learning a new piece by playing it really slowly and ever so slow ratcheting it up supposedly prevents practicing mistakes. However there are not infrequent times where the correct way to play something is not apparent except when playing at or near tempo. In those cases practicing really slowly all the time leads to having things that have to be unlearned to be able to play at tempo.

If you are playing a piece that just does not feel quite right to you it may help you to listen to a few other people play the same piece and carefully analyze any version you hear that you like an perhaps incorporate some things.