> IMO, 99.9% of the time you don't need the more obscure data structures
Absolutely, and familiarity with these data structures is what's required to prevent these mistakes. I think a good understanding of these is more likely to prevent one from using them, or in some cases, "inventing" them.
Though another way to avoid making the mistakes is to not invent data structures. That's what libraries are for, and anyone not using a library data structure should be able to defend why they're not. Odds are, they've got no chance of writing something better than what the libraries provide (or they'd be a library writer and already know these things).
Absolutely, and familiarity with these data structures is what's required to prevent these mistakes. I think a good understanding of these is more likely to prevent one from using them, or in some cases, "inventing" them.