I don't think there's any need to worry about not having time to max out confidants etc in NG+. I am still on NG (at the end, last confidant date has passed), and I only had 4 confidants that weren't at rank 10 and I wasn't even really trying. It was like, Ryuji/Yusuke were are 8, Ohya/Iwai were at 5. Everyone else was at MAX!
Hell in December I just skipped a bunch of days to get on with the story. More than enough time to do them all, really, if you make sure to use Chihaya and also - I haven't seen this mentioned much - I went to the shrine to pray just before the end there and I noticed it also raises your confidant levels. Couldn't you combine this with Chihaya, do both on the same day (one in afternoon, one at night) and get even more of a boost for the confidants?