Depends how much time and how many kanji you are making yourself go through really right? I found that i pretty much get 68% everytime when it comes to reviewing a yellow stack or a blue stack (which i leave up to 24hrs at times). If the yellow stack is on the second pile i get 90%+ so far.

It's all about how many cards you end up using at a time. I found after i slowed down my rate went higher...but to keep up with my goals i'm going through a little faster because i realized that you still get the same result, just reviewing more