How many 4x7 "challenging" puzzles exist?

[thequeenofspleen]

When you set the parameters, for example 4x7 grid size and "Challenging" difficulty, the next button you hit is "generate puzzle." Is the puzzle actually generated, in the sense of having a selection of names/attributes picked out from some big database and dropped into a set of viable clues, like a fill-in-the-blank situation? Or is there a bank of pre-made logic puzzles of each type, and it just randomly selects one for your parameters?

I feel like it's probably the second option, since I see people posting multiple comments on the same puzzle victory page (like "232s" in March 2019, and then a year later "220s" or whatever), which implies they've gotten the same puzzle, which implies a puzzle bank. But I'm not sure. If there is a puzzle bank, how many 4x7 "Challenging" puzzles are in it?

[ella]

There seems to be a puzzle bank because we certainly play the same puzzles multiple times if we play long enough. Not so few that it's possible to memorize or anything (especially because there are multiple puzzles using the same types of clues, same names, etc.) But there is a finite number, it seems. I have no idea how many challenging puzzles there are, but I would imagine that it is similar to the rest of the sizes/levels.

[fromalabama]

I am not certain, but I think the only difference between the 'Challenging' and 'Easy' or 'Moderate' puzzles are the clues provided. I believe the grid and solution for any given puzzles are the same across levels. There may be about 10,000 or so permutations of around 120 themes for the 4x7s, although there may be more for the smaller sizes since the categories can be divided up more ways. I also think that when it is 'generating' a puzzle, it may be randomizing the order of the clues available for the difficulty selected. Different people take different approaches to which order they find best to apply the clues, so mixing up the list from top to bottom might have some effect on solving times.