Book - Make it stick.. the science of successful learning argues that extracting rules from commonly encountered problems is an essential skill for applying the knowledge to different problems:
When you’re adept at extracting the underlying principles or “rules” that differentiate types of problems, you’re more successful at picking the right solutions in unfamiliar situations.
They claim that people differ in their ability to do this, resulting in Rule Learners vs Example Learners
Interleaved and varies practice helps with acquiring this kind of skill acquisition. You can think about massed practice as some kind of "overfitting" on the problem set you practiced it on. The book presents various studies to argue that Learning is more efficient when it is varied and you practice interleaving