Keep in mind that the majority of the use of puzzles is merely to delay/use up player Actions, and not trying to stump the player with a new puzzle. Even if you have a puzzle memorized, your character will need to use up actions to actually solve it and will be delayed from doing other things. So, while I think there will be enough variation in the puzzles to keep things fairly fresh, it shouldn't be a big deal if you are already "know" the solution.
yeah you're right. But I also suspect beside just a time delaying /action consumption thing, I fear a hidden timer once a puzzle is revealed. Some may be as obvious, like the sound of a large creature stumping closer, about to round the corner of the corridor, and you need to get the circuit right to open the vault.
others might not have a obvious "tick-tock" to it, but I assure you I will be very suspicious and anxious to solve the puzzle once it revealed. "uhm, is it just me or does it appear that the shadows are growing arround us? hurry you better get that lock upon anytime soon, its getting darker and colder":