Players Handbook p31 states
Before a wizard can actually cast a spell, he must memorize its arcane formula. This locks an energy pattern for that particular spell into his mind. Once he has the spell memorized, it remains in his memory until he uses the exact combination of gestures, words, and materials that triggers the release of this energy pattern. Upon casting, the energy of the spell is spent, wiped clean from the wizard's mind. The wizard cannot cast that spell again until he returns to his spell book and memorizes it again.
Also, PHB p81
Memorization is not a thing that happens immediately. The wizard must have a clear head gained from a restful night's sleep and then has to spend time studying his spell books. The amount of study time needed is 10 minutes per level of the spell being memorized. Thus, a 9th-level spell (the most powerful) would require 90 minutes of careful study. Clearly, high-level spellcasters do not lightly change their memorized spells.
Spells remain memorized until they are cast or wiped from the character's mind by a spell or magical item. A wizard cannot choose to forget a memorized spell to replace it with another one. He can, however, cast a spell just to cleanse his mind for another spell.
And yet, a 3rd party compilation of spell acquistion rules states that 2e differed from 1e by bringing in a daily limit, suggesting a summary like this:
Anytime after your have slept for 8 hours or more, even if you have cast any spells, if it has been 24 hours or more since you last memorized a particular spell slot, you may fill that spell slot again.
Reading between the lines of p81 ("a restful night's sleep") suggests there is a daily limit, but also suggests that the sleep must occur during the night (i.e. no mages on a nightshift schedule) .. but that seems .. too much.
The priest Nap spell says:
Creatures affected by this spell are put to sleep for one hour. Upon awakening, the creature is as refreshed as if he had slept for eight hours. The affected person recovers lost hit points as if he rested for a full night. Wizards can memorize spells as if real time had passed.
.. but no mention of any daily limit (and also doesn't say "as if had slept [at night] for eight hours").
So .. other than a particularly lawyerly parsing of p81, is there any specific mention of a daily limit for spell memorisation (or other rules text for guidance)?