Confusing, I know.
When performing a chudan block (for example), you should not try to make your block as high off of the ground as mine. You should make your block even with the part of your body where mine is on mine. So with a chudan block, your hand should be as high as YOUR shoulder. If your block is as high as my shoulder it will be too high (unless we're the same height).
Osensei has said many times, "Your karate grows as you grow." Like many of the things he says, it carries more than one meaning. It means that your techniques should physically grow along with you so that they always fit your body. It also means that your understanding of techniques that you may have known for years should also grow as you develop as a martial artist.