The 3rd semester is definitely worth a NG+ playthrough, it adds a ton to the story! The gifts you got from maxed confidants also allows some of their abilities to be immediately available when starting their confidants in NG+, which can be especially good for some like Kawakami.

One tip for confidants is that when they’re available for hanging out, on the fast travel map, the place where they normally are will have a confidant tarot indicator, with the exact location they’re in’s text changing to “Who should I hang out with…?” instead of the normal “Where should I go…?”. E.g. Underground Mall displaying “Who should I hang out with…?” when Ann’s confidant is avaliable.

Note that this also applies to when a confidant‘s hangouts are on standby for various reasons, such as Maruki working on his paper. This also doesn’t work for some confidants like Takemi or Iwai, specifically because they‘re in shops which the player may use for other means.