10 years training in 35

How important is it to ensure you always train using your little idea? Surely you can get the same effect by making sure you really intellectually understand what is happening?

Let's put it in simple numbers. Sifu has been training for 35 years. He said that if he had been training the way he teaches now it would have only taken 10 years.

That's 25 years of extra training. 10 years was under a different lineage so it makes sense that he didn't make any progression in this style. Since then he has been training under Chu Shong Tin (my Si Gong) and he spent most of his time asking questions trying to understand the movements, the little idea, intellectually rather than actually training the movements. 

Also, at that time Si Gong didn't understand the best way to teach and explain what he could do. He could show people what he could do and tell people when they were doing it correctly but there was little explanation. 

Understanding is not enough. You have to practice doing it to get better.