Is 5 as much of a chore to play as 3 and 4? I know the day-to-day progression is still there, but is there at least interesting combat or social links that actually feel like they mean something this time?
Didnt play 4 only three so my opinion may not matter much. The combat is more or less the same but you have more "elements" to play with its still only " get enemies weakened to get extra turns. You have some fights where you have to do some special stuff to hurt the enemie but that is rare and only ends with you chosing someone who does whatever is needed where you hack away at the boss with the remaining party. The confidants still mean nothing, either you like their stories or not, they give you special skills which are useful but not really needed.
The only thing that is really needed is the baton pass skill which you get with every link in your core team which allows you to pass the turn over to another party member after you weakened an enemy effectively skipping the turn order and giving that member an extra turn this round. Other examples are extra ep for backup members, being able to switch backup members with active members in fights etc. Everything is useful but some more than others and aside form the mentioned baton pass I wouldnt call anything on the list strictly necessary. Maybe the switch option but only if you play on higher difficulties to have easier access to buffs and debuffs in a fight (instead of having to rely solely on the main char to provide the neded skills)
The story is still told through main scenes and while confidants may have main story related stuff to tell you theres nothing that gives a deeper insight into the main story, it remains extra fluff.
You can break the gameplay into roughly 3 parts, 1 being railroaded into a new palace 2. doing that palace while having a deadline 3. the point after you did the palace until the deadline arrives and your back to 1. A palace will always take two days to do at least, some palaces take a bit more time since you may be kicked out of it due to story reasons. Only after you finished one you are truly free to do whatever you want (until the fallout of your actions when the deadline arrives).
I dont think its possible to max everything and do everything in one playthrough if you play blind but should be possible if you use a guide.
Romances dont get acknowledged outside of special events with that confidant. Contrary to what the internet might tell you there are no gazillion different endings. Theres a game over sequence for every mission you might fail (meaning not finishing the palace in time) and one for failing the interrogation that starts at the beginning of the game. Whatever you do while playing you cant fuck up by not leveling a confidant or being somewhere at date x instead of being somewhere else at date y or giving the "wrong" answer. Its either game over or the game goes on.
The only exception is more or less at the very end when you talk to the big bad and he pretty much asks you "do you prefer ending a or b". The game will tell you that this answer is important. The game also warns you when you get to a high confident rank and the conversation might lead to romance so that you dont lock into romancing someone "by accident".
Theres also NG+ which is more or less worhtless since it doesnt add anything to the game aside from an extra persona you may only fuse in new game+, and some stuff you carry over from the first playthrough but since nothing in the game changes that becomes redundant.