Nope, you're right. It's not definitive. In my original comment, I just said I thought I remembered reading somewhere that you couldn't fit >30 hrs into a day, and the passage I quoted is where I got that impression. If /r/hpmor thinks it's possible that TTs let you fit up to 48 hrs in a day, then I have high confidence there wasn't anything explicitly forbidding it in the story.
Just to be clear, the Reddit thread didn't say that you can fit 48 hours in a day, it just didn't say that you couldn't. And it probably had that Dumbledore quotation too, it's just me saying that we can't know for sure what that quote means.
This is a new thread to discuss Eliezer Yudkowsky’s Harry Potter and the Methods of Rationality and anything related to it. This thread is intended for discussing chapter 116.
There is a site dedicated to the story at hpmor.com, which is now the place to go to find the authors notes and all sorts of other goodies. AdeleneDawner has kept an archive of Author’s Notes. (This goes up to the notes for chapter 76, and is now not updating. The authors notes from chapter 77 onwards are on hpmor.com.)