I think it's important to always be learning. If you don't know what to play on an E7#9 chord, then that's what you should practice. Find the scale, harmonize it, learn it's arpeggios, it's pentatonics and play with the notes. Sometimes if you sit for 10 minutes without the guitar just to decide what you are going to learn in your practice time, that's good. If you can play over an Emin7 chord, move on, it will still be there when you get back. The bottom line is Quality time is more important the Quantity time.
( Turn your worst enemy into your best friend. - Ed )