24 hours is good for people when they want to get things done quicker. 48 hours still get the job done too.
But some people might not have time to actually participate in this case because they have a job or something else that takes a lot of their time.
However, making the phases longer, while allowing those people to play, also puts them as a severe disadvantage because the ones who could still be around for the shorter phases become much more active than them as a result, leaving the busier people a relatively smaller amount of time to share thoughts or defend themselves.
As such, despite the fact that I really want to play again, I'd rather advocate for a shorter time. It means less people can actually play because some are busy, but it also means the ones who can show up will theoritically be participating more, creating a smaller amount of inactives and thus, a more active game.
Be it 24 or 48 hours, I don't care. If I feel that I don't have enough time to commit, then it's probably a good amount of time for a mafia game.