Celebrim
Legend
Really? Virtually every treasure roll had about a 10% chance of 2-4 magic items. That meant that killing a single troll (trolls came in groups of 1 as well as groups of 10) could net you magic items. EVERY lair had about a 10% (give or take) of multiple magic items.
Even if we take what you say as truth, that would mean that you'd have to kill about 55 Trolls to find a magic item stash. It's actually worse than that though. The number appearing on trolls is 1d12, and only 40% are encountered in lairs. Trolls are treasure type D, so every 108 trolls you slay you find about 2 magic items and one potion (which, if it is useful, the trolls are likely to drink). One third of magic items are potions or scrolls, so really its about 1 magic item per 108 trolls.
And actually, it's worse than that. Because while trolls can come in groups of 1 as well as groups of 12, groups of 1 do not in fact have the same amount or chances of treasure as a group of 7 or 12. Per those little regarded and little read rules of 1e AD&D that always seem neglected:
"Finally, it must be stated that treasure types are based upon the occurrence of a mean number of monsters as indicated by the number appearing and adjustments detailed in the explanatory material particular to the monster in question. Adjustment downwards should always be made for instances where a few monsters are encountered. Similarly, a minor adjustment upwards might be called for if the actual number of monsters encountered is greatly in excess of the mean."
Notice typical Gygaxian logic - you definitely should reduce the chance or amount of treasure if the encounter is easy, but you only might should increase the chance of treasure a little bit if the encounter is hard.
How many lairs would a party have cleared out by, say, 7th level?
I've done the math before. If you are relying on lairs for treasure rather than published modules or placed treasure, you are playing a very gritty game indeed. If those are your standards, then I assure you that magic is rare and highly prized.