Best exercise studies

[savvygal]

Hello, My teacher has been giving me Czerny's eight measure exercises for exercise practice, which takes me a lot of time in my practice sessions.  We abandoned Hanon recently.   I have Brahms' 51 exercises and I think those would be better, although some of them are hard but I feel I could master them in shorter time (well, some of them.)  
The problem is, the Czerny exercise are more like learning a piece!  It takes me a month to learn one of these.  I feel like I'm not getting ahead taking so much time to learn an exercise.  My old teacher had me doing Hanon in so many different ways that I feel that was probably more productive.  What is everyone else doing that they feel is productive?  I'm at a level five or six but more like four with no major stumbles.  I do have a level seven piece I'm learning.  Thank you!
Is repitition the key in exercises?