I've always had this thought about the protections around the stone in the first Harry Potter book: they didn't seem to be very good protections at all.
They seem more like skill testing challenges, which make absolutely no sense in terms of providing any sort of protection. It's like setting the bank vault to open for anybody who's skilled enough to solve a series of highly challenging Sudoku puzzles.
It does make sense if you think of it in another way though. What if those challenges weren't meant to protect the stone at all? Perhaps the object at the end of all the challenges was a fake, and these "protections" were just a scheme that would cause anybody seeking the stone to waste their time on a fruitless pursuit.
They had to make the challenges difficult, but potentially solvable in order to keep any would be thieves busy so that they would be too occupied to think about it and guess the truth - which is that Dumbledore was carrying the stone around on his person the entire time.
This is the kind of strange theory that I come up with once i a while