Guaranteed? No. But if you play a lot of TSR-era adventures (modules, supplements, and Dungeon), you're going to have so many +1 swords, shields, and rings of protection you won't know what to do with them all! My current 5e game is based on me converting a lot of old favorites, and even with me massively reducing the amount, there's still a lot of swag! It really made for quite a bit of whiplash back in they day- I'd have other DM's claim that magic items were super rare and you should be lucky to have a +1 knife at level 6...and then I ran Terrible Trouble in Tragidore (it came with my DM screen, it must be a good starting adventure, right? LOL) and by the end, the characters were dripping with loot!
"Oh well, I mean, you're supposed to modify printed adventures", they told me. And I was left scratching my head. "Where the heck does it say that?!".
I mean, heck, Fighter's Challenge, supposedly a solo adventure for levels 2-4, offers up a +3 (!) weapon about 2/3 of the way in! I mean, granted, it's a warhammer, which is a lousy weapon in AD&D, so, yeah. But still!
Let's just say that you got a lot of mixed signals about magic item rarity in those days from the publishers.