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Quite obviously, almost nothing will stick if simply mentioned/explained just once or twice during the schooling process. Its usage has to be incorporated into the process kind of like when you learn basic algebraic formulae and then apply them countless times during the years to come so they become a thing as ordinary as your own hands. You can still forget precise correct formulae after some years of non-usage but you will never forget they exist and you will always know you have to look up or derive a specific formula once you encounter a relevant problem.