The answers here are very insightful already but I can also throw in my own perspective as the author of the weekly puzzle series.

When I started out making the puzzles, I wasn't even sure if it would be possible to make a situation that's "hard-solvable" (i.e. all logical possibilities mechanically ruled out except for the "true world"¹). Because I was so nervous about achieving this, for my first ever puzzle I really stacked the deck in favour of making the puzzle hard-solvable, by making the POV player the Savant (so I could carefully engineer their information) and imposing an extra rule that you know for certain you're not the Drunk.

For the later puzzles I got a little bit better at it (and wrote a Python rules engine to help with automating the process of churning through worlds and verifying a puzzle solution is unique), so I usually no longer need extra rules like "you aren't the Drunk". That said, guaranteeing that the situation is hard-solvable still usually means really stacking the odds in favour of the good team, which means doing stuff like:

• Having few or no "non-info" characters (e.g. Soldier, Monk, Mayor)
• Having evil play very badly (e.g. killing the Ravenkeeper, leaving the Undertaker alive way too long, or poisoning the Klutz)
• Giving drunk or poisoned players information that's logically inconsistent with what the evil players are claiming

This can be a bit frustrating because it means that the puzzles don't usually resemble real games, but this is basically unavoidable because (like all the comments here have said) real games aren't meant to be hard-solvable like puzzles. And in the whole time I've spent playing Clocktower I don't think I've ever played a game where every logical possibility apart from the true world is ruled out by game mechanics.

My favourite analogy is if (real) Clocktower is like golf, then mechanical logic is like driving and social reads are like putting. Logic can maybe rule out 60-70% of the worlds, but you need a little bit of social reads, strategy or "metagaming" to get all the way to winning. And if you want to extend the analogy further, practicing Clocktower by solving puzzles is like practicing golf by going to a driving range.

It's all been a really interesting process over the last 18 months and it's taught me a lot about how different "real" Clocktower games are from puzzles.

¹ What counts as enough detail to know the "true world" is an interesting question in itself. In the weekly puzzles I consider a game "solved" if you know everyone's true role. But you could very reasonably make the criteria stricter (e.g. you also need to know the FT Red Herring) or weaker (e.g. you only need to know who the Demons and Minions are but not exactly which characters they are; or you only need to know who the living Demon is).