Really Slow

OCT 16:  When you practice a passage so slowly that it fails to make sense as music, you are really learning where the muscles need to go in order to make the passage work.  At faster speeds, you may need to change the fingering---- but you'll still have the basics with really slow practicing

The problem is that it becomes more difficult to do it really slow, usually, than doing it at a moderately slowed down tempo.  Your memory has to strain for the details, because the details are now distorted to the point where the natural flow of the piece is lost.

But as you take the passage gradually faster, you find the going easier because now everything is more in context.  That's why context is so important.  And that's why music is not just a bunch of notes strung together.  It all fits somewhere.  Really slow practicing shows some things about the music that aren't obvious at normal speeds.