Proficiency before moving to other works

[james88]

Hi All

I have been playing piano on and off for 30 years, I also play a lot of guitar. I know a lot of theory, jazz and classical, but I have never taken lessons for piano. I can sight read anything of difficulty,- a strong knowledge of harmony helps- albeit slowly, although I can often play either hand at speed (I have good fingering choice I think). My question is for those that have teachers or are so (I am currently reading a lot of Czerny exercises)- is one expected to be able to play something perfectly before moving on to harder material? I enjoy playing the hardest things I can find and would rather turn thru books of Czerny exercises playing thru each each exercise twice only before moving on. And so, nothing is perfect, although I do get better at reading things unseen as I work through more pages. I have had teachers on guitar who thought it was very useful to not get struck going over and over something but to keep moving forward, eg, with scales, just keep moving around the circle and don't get too stuck on one scale, just keep working them all, as they will all improve eventually. And I have met some great players who had poor memories but could read anything brilliantly. This is what I am working towards.

So, what advice do professional teachers and conservatory type schools proscribe when it comes to playing through books of material, albeit exercise/etudes or preludes and fugues?

Do you pick a few pieces to get up to speed and flawless before moving on (I don't expect to have a performing career as classical piano player, but I would love to be able to play the 48 at sight, well), or do you have a lot of material to work thru? And, given the maximum speeds given for Czerny (and, I feel, they can be played slower - have to be - since a student cannot march up and play it at sight at top tempo), do you keep working on a single piece until its at top speed before turning the page, or work through them all at a slower tempo and come back around again later to do it better and faster a second time through the book? I'm kind of in an in between position where I can read the harmony of anything well and appreciate it, but only have so much time to devote towards performance perfection. Would I be better off mastering a few things only, or continue though as much sight-reading as possible? Trouble is, I get quite bored working through on one piece, and don't see myself ever performing these things, so I keep turning the page to enjoy the next difficulty..do I go back and master the stuff at tempo (grade 5ish), or work on hard stuff (48, Chopin, Czerny).
Of course, this question has been asked a million ways; (what do I do with my life to be better)   

[anacrusis]

I think you need all of it. A large quantity of not too challenging pieces that you can read reasonably well to grow your reading skills, AND a few pieces that are within your technical reach that you polish, AND a few pieces that are a bit too hard but challenge you to grow. You might do that all at once or alternate depending on what works for you, but I think all of those things are pieces of the puzzle.