2e I don't have the weirdly vivid recall that I have with 1e.

But it did have to be from the specialist's school, FWIW.
The 1e new spell when you get a new spell level...
...actually, all 1e spell acquisition not simply cribbed from spells or spellbooks was... unclear.
Quite a number of things un-naturally aged you in 1e, particularly otherwise desirable/beneficial things, from Haste to Wish, as a limitation on abuse, in theory (and age-reduction magic always carried a risk of unwinding on you), to the point that the standard 1e goldenrod character sheets had separate space for Age, apparent age, and unnatural aging.
And (though I'm sure this varied wildly) once you got into mucking about with strongholds, the campaign's time frame might shift.
Funny thing, though, there were like three different versions thereof. A cursory PH treatment, CPH, and L&L, I think. I preferred CPH and used it extensively for years (from the DM side of the screen), L&L sounded pretty broken.