Many of the most fundamental ideas in magic are many years old ... sometimes over a hundred years old. The best ones live a long life and find themselves evolved into more devious and subtle handlings by more contemporary sleight of hand artists as time goes by. Some of the best tricks today are rooted in these 'hundred year old ideas' ... some combined into more complex presentations w/ mulitple reveals.
There's also quite a few of the hidden sleights that have their roots in the wilder days of saloons, card playing, and gambling. Cheating of course was the end and hidden moves w/ the cards was the means. False Shuffles, false cuts, side steals, second dealing, palming, etc are all the the tools of the card cheater (gambler). Due to their devious efforts we card conjurers have a broad palette of subtle manipulations to use for our magical presentations.
Each new idea (or modification of an earlier idea) can be shaped into a new form that many can call their own. This is most true when speaking of the
Classics in Magic. It's actually pretty amazing when you see the ideas some come up with ... seemingly obvious ... but not until it's right there in front of you does it seem that way (hey, why didn't I think of that).
Even though I haven't been doing magic for very long, I myself have even been able to take an effect that was 'structured and presented' in a certain way and modify it a bit for my own liking ... one that I feel more comfortable with ... and what I think presents more mysteriously and magically.