Because for a couple reasons...
The level of the puzzles...chess.com gives you random puzzles based on your level. If it's puzzle rush, though, the puzzle are always the same.
The puzzles aren't exactly repeats all the time but just very similar
Hmmm, interesting. Thank you.
They say they have over 500k puzzles, but I get a lot of repeats.
Hence why I have my Tactics, not to mention my Puzzle Rush Survival score!
Why?!