[101008]

My experience with people who are PhD is that they know things you expect to memorize just because they use it a lot. They learn formulas or whatever not because they spend 5 hours memorizing it, but because they needed it once, so they looked it up. The second time they needed it, they weren't 100% sure, so they looked it up again just in case. Every time they search for it, they need it less and less and at the end they know it by memory. That's how you learn most of the stuff these days and that should be for everything. Natural learning. Why memorizing things you dont need to know?If you use it often enough, you'll end up memorizing it. Same for concepts or any type of knowledge.

[twic]

I can tell you the peak excitation wavelengths of a dozen fluorophores. Not because i wrote them on flashcards and memorised them, but because i spent four years in a darkened room sliding filter cubes around to take pictures of slides stained with them!

[politician]

There's a term for this and several software packages to help exploit the effect.

https://en.wikipedia.org/wiki/Spaced_repetition