The first is regarding how we perform techniques. As beginners we learn full, large movements; three-hip punches, the formal setup and execution of mawashi-uke, chambering of kicks and punches. These are to train us in correct form and power generation. As we develop, however, we should not be keeping the same large, overt movements, but should be internalising them while keeping the same feeling and function. In other words, going from big to small.
The second is how we perform kata, and is very much related to the "big to small" concept. There is a standard way we learn to do kata, with standard applications that are learned as we do. But this is again a learning technique. A kata, while coreographed, should have personal meaning to the person performing it, and will change slightly to reflect their understanding of its principles and the applications they associate with it. As my sensei said to us recently; "if you are teaching it, teach it this way. Then the important lessons don't get lost. But for yourself, if you want to do it [an alternate, or differently emphasised way] differently, is that wrong? No, as long as you know why you are doing it that way and it works with the principles of the kata".
So, big to small and standard to personal; easy to say, hard to do