IM Rashid Ziyatdinov published GM-Ram which contains 253 positions and the reader is invited to add 47 others that they find meaningful to them. He also includes 59 games every developing master should know. Oh, there's no analysis; you're on your own.
In Understanding Chess Middlegame John Nunn lists 300 ideas you have to know. How many puzzles are there in The Gambit Book of Instructive Chess Puzzles by Graham Burgess? If you guessed 300, congratulations!
The Chess Strategy Course offered by The Internet Chess Learning Center offers which contains more than 300 chess study problems. There are probably other examples, but whatever these 300 positions are, you have to know them fully which includes understanding everything about them and being able to recognize them instantly. The same can be said of the key games you should know by heart.
So, the question is, how do you remember all that stuff? So far I have not seen a book titled How to Memorize Chess Poitions. Anybody want to write a book like that? My guess is it would not even have to be very good. With the right hype, chess players would snap it up.