I would say that the best efforts of those engaged in teaching chassanim and kallahs are still wholly inadequate.
It’s supposed to start with their parents, from when they’re babies…
If someone has the proper morals, values, and middos they’re supposed to get from the chinuch they received, chosson/kallah classes could be useful.
If not, even the best instruction would be like putting a bandaid on a deep, gushing wound.