When you climb a mountain and you see a peak, you think “oh, this is the mountain top, let’s push and get there to the end of the journey”, when you get there, you realize that there is another peak you could not see until you got to where you are, and than you keep going and keep finding out as long as we live.
When we learn a technique, we can only receive so much information, and as we train and gain experience we have tools to get more details, and than we realize that the simple techniques have infinite levels.
Sensei Nishiyama used to teach some details of a technique, let me struggle with them, digest them, and than a year or two or five later he would tell me another small point that changed the way I looked at that technique, and I used to think “why didn’t he tell me those details right away?”
Later I realized that until that moment I was not ready for those new details, and when Sensei Nishiyama felt that I was ready he would go deeper into the technique.
We cannot do techniques mechanically, practice, digest than contemplate and the potentials for development is unlimited.