It is just a matter of forming a habit. Pure raw data requires good scan which requires practice but once a pilot develops it, it shouldn't require much practice to maintain it. The problem is with everything normal you don't need all this so unless you force yourself good habits can get rusty.
Vilas: well said, but there is one problem, and that is with the starting point. I agree with the process, but today's training doesn't require the students to 'develop a good scan'. Neither does every day operations in many airlines. Therefore there never were good habits and therefore the rust is deep seated from the beginning and the metal corrodes fast until there is no strength when it is tested under stress.