One of my favorite principles of effective instructional design has always been "use it or lose it". When we fail to use something we presume we have already learned, it's not there when we need it later. We forgot it because it seemed useless at the time we were exposed to it. Much like a library that pitches the books that no one has checked out for a decade, our long term memory acts as if cognitive housekeeping is routinely required.
Use if or lose it also applies to cramming for tests. The immediate use of the new knowledge involves coming up with it under test anxiety in order to get a good grade with it. Our minds can handle those short term uses on the basis of usefulness, just like they approach long term retention. However, that cramming use is obviously temporary and the knowledge is soon forgotten. College students agonize when it gets announced the the final exam will cover the entire semester, not just the second half. They've just become aware that all that "useless" stuff from 6 weeks ago is going to be useful for another crucial hour during the final week of class.
Learning by doing, praxis or social interaction is a different story. The "context of use" is immediate. The value in knowing it is evident and convincing. When that practiced use gets reapplied in another situation, retention is effortless and enduring. There's no cramming required. Our memories work superbly. We've learned the way that works for our minds, our conduct and our reputation.
This principle implies that instructional design ought to create "contexts of use" rather than contexts of informative content delivery, required reading or contrived memorization. It's much more difficult to create situations where the information gets used when starting from a bunch of expertise to deliver. It's much easier when starting with problems to solve, crises to alleviate or conflicts to resolve. Then the content will either be presented as tools or deleted because it's not applicable to those use cases. Then use it or lose it applies to editing the content of an instructional design, not just the retention strategy of the participants.