The solution to the problem of too much work for too little wear, is free-sole socks. These socks are knit so that the whole sole or any part of it can be removed and re-knit leaving the rest of the sock intact. The whole sole is made of one yarn, the rest of the sock with another. You might want to do this if you are using a precious yarn (e.g. cashmere) for the rest of the sock and want something sturdier where the wear is greatest. Or you could use the same yarn for both and use this technique only because you are putting a lot of work into the upper part of the sock.

Anna Zilboorg from Socks for Sandals & Clogs