I think it depends on how you manage your schedule. To each his own I guess because I use the Library often.

The Library is worth using only during pre-exam periods, where most S.Links are unavailable thus you don't quite waste your time. Studying at night has the advantage that there isn't much to do at night except level up the Monk S.Link (Tower, I think), and that's only on certain days

That's not bad, but I you really need to work on it. You study every night that you aren't in Tartarus. You need to be playing games in the arcade to boost Courage, Charm, and Academics. Academics is the hardest to raise. It needs more than double Charm and Courage to max. And you also have to have max courage before you can start the Fuuka link. You must also have max charm to start the Yukari link.

And you need max Academics to start the Mitsuru link, which is one of the best links in the game, everyone needs to max that link. And Academics is worth to max it ASAP, you don't have to worry again for exams and you're pretty much assured to get the top mark

I'm 5/6 for Academics. I know I have to max it before late August. I figure I'll have to start it late.

I'm going through the Summer Festival at the moment.....

I don't remember when you can start the Mitsuru link. Though I'm sure I didn't max Academics very early in the game, so you got time. That said, I didn't max the Yukari and Fuuka S.Links as I did with Mitsuru, maybe I had maxed the stats before I could have gotten a better chance to max them

You can't even start the links until you max them.

I started working on the little girl at the shrine now. Her story is very sad.

Well, my opinion about S.Links a Ultimate Personas. Oh, andit´s not about how good personas are, but as I like them too. I refuse to run around with some stupid persona, every one of them must have some style. Maybe some spoilers, so be careful.

Magician: First Link, you probably complete it. And is interesting too. Surt is good persona, has Ragnarok, powerful fire attack.
Priestess: I don´t like Fuuka and I don´t like Scathach much. Story isn´t really interesting.
Empress: Story is good, but Alilat is meh. But when I finnaly get Misturu, I have done nearly everything else..
Emperor: I like that S.Link, and Odin too. Thunder Reign is pretty usefull.
Hierophant: Interesting story and one of my favourite personas, Kohryu.
Lovers: Ewww, I´m not fan of Yukari, so please, go tell your problems to someone else. Cybele isn´t my favourite at all.
Chariot: Interesting story and persona Thor
Justice: great girl, my second choice, but persona Melchizedek isn´t much.
Hermit: Now, that´s a S.Link. This is given, everyone should try it. Roflcopter. Persona Arahabaki isn´t that good.
Fortune: No good, story and persona Norn alike.
Strenght: I like Yuko, story is interesting. Siegfried is good.
Hanged man: Apart from that you feel like pedo, good story. Attis isn´t good, though.
Death: automatic, not much choice. But persona Thanatos is good, Die for me! is great. Btw.: that´s the persona from beginning.
Temperance: No, both story and persona Yurlungur are bad.
Devil: Really great story and Beelzebub is my favourite persona too.
Tower: Interesting, Chi-You is good.
Star: Good story, really great persona, Helel.
Moon: awful story, Sandalphon is good.
Sun: Interesting, but sad story, Asura is pretty good.
Judgement: Automatic, Messiah is taht good, as it should be. But looks good. And two personas before him, Satan and Lucifer are great.
Aeon: average story, but Metattron is great.

Well, something like that. But it´s only my opinion.

I know. But you can't start the links until after some point in the story also, don't remember which exactly

It's June 26th for Fuuka, and July 24/25th for Yukari. Not sure about Mitsuru.