Chris, thanks for sharing your valuable experience. Interesting results, remaining questions. Will continue to ponder!

Take an area I know best, and is well-studied, programming. Programmers have many very specific programming skills, right down to particular tricks for particular versions of particular programming languages. But they also apply very general skills for designing and debugging code.

There have been numerous experiments giving novice programmers very general frameworks for breaking a problem down into implementable parts or systematically finding the source of a bug. The studies I’ve seen — to be fair a tiny slice of what’s out there — have had modest benefit at best, over a very narrow timespan and range of exercises.

My personal bet is that after a great deal of specific personal experiences, students have implicitly learned general skills, at which point a codification of the abstract ideas makes sense and can help organize ideas already know a bit better.