From Bertrand Russell or was it Alfred North Whitehead...."the goal is to have no problems only exercises".
By expanding long term memory one can turn potential problems into exercises.
It seems that the goal of many pushing the discovery/inquiry approach is to have no exercises but only problems. *
I am still in shock from Dr. Ruth Parker's powerpoint given at NCTM national that the Standard Algorithm always harms conceptual understanding, which seems to be a recipe for lots of problems.
The person most everyone would like to hire is the one that has so much extensive background knowledge that most everything is an exercise.
Here's Ken on the subject of struggle:
* students must struggle