Union-find is one I find needing a fair amount too, although it does make algorithms tricky to debug if the problem is a bad union ("which union was the bad one that caused all these groups to collapse into one?").

But even for these simple data structures, I am much more comfortable implementing them with an algorithm textbook in front of me (or some other resource with similar level of detail), simply because it greatly reduces the scope for implementing the data structure itself incorrectly and, secure in that knowledge, I can focus my debugging on the algorithm itself.