Schools take up 1 space, and add 25% to the town's tech.  For 3 gold per turn.

Studies cost 1 gold, take 1 space, and provide 1 tech.

So unless you are very pressed for space, a school provides a slight acceleration when you have at least 4 studyies (or libraries), and makes financial sense when you have 12.

Except that any town you are really interested in tech for, you are going to pick tech as a city advancement.

At that point, using libraries, you are getting effectively 3 tech for 1 space and 1 gold,

At 6 libraries, you get 3 tech for the 1 space and 3 gold for the school.

And for it to make financial sense, you need to have 18 libraries.

18 Libraries?

And if you have any other tech bonus (10% for being Capitar?) it gets even worse.

Now, I suppose if you had a lost library that would shift things.  Then the School would give 1.25 tech in addition to the bonus for the studies / libraries.  the only problem is that Lost Libraries are so rare as to be almost irrelevant in evaluating the utility of build options.

It seems that the school should be adjusted somewhat.  My suggestion would be to reduce the maintenance cost to 2 instead of 3.  Admittedly, in practice, by the late game, money is not an issue for me.  But It seems like it should balance better.

Yours,

Joel