Hmm. I don't think I've seen a rec post for any fandom I'm active in at any point in the last decade+ though I do sometimes look at people's recs after exchanges reveals. Those are generally sorted by fandom only.

Even thinking of longer canons, I think things like place-in-canon would be easily conveyed in notes - I'd probably just sort by featured characters or pairings, then have 'post-canon' or 'x-arc' in the notes, along with any content warnings.

A lot of recs I see just use the AO3 tags as well.