[SamBam]

Why such a large number? Do players really go through thousands of puzzles a month, and remember them all?

If you produced fewer, would that increase the proportion with expert review?

[Nemerie]

Casper Schoppen broke all the previous records in puzzle rush (a mode where you get to solve as much puzzles as possible in 5 minutes) by memorizing most of high rated puzzles. After that chess.com decided to add a lot of new ones.

https://www.chess.com/article/view/puzzle-rush-confirmed-rec... https://www.chess.com/news/view/new-puzzle-rush-chess

Although I don't think there were lots of players who tried to use this tactic among all the ones who occasionally train on chess.com.