Speaking as one who learned years ago, when buddy boxes were just starting to be available, but certainly not common, and sims were not even imagined yet, I can say that this method of training works. I personally think that NO student should be told to go spend a few hours on the sim before working with an instructor. As has already been said, unstructured learning is very likely to create bad habits which then have to be untaught. Sims should be a secondary training aid, something to allow the student to reinforce what they have learned from the instructor, not a primary means of instruction.