So the 5.5 DMG does have guidelines for magic items. Depending on DM its almost one every encounter or two. Note a lot are common items but still.
In the 2024 starter set they use a random item deck of cards. Every cave seems to be 2 or 3 encounters and 1-2 items and various other ways to get them.
My group popped +1 full plate in the goblin cave. RAW 1 rare item can drop level 1-4. I've been used to such items dropping since the 90s and 3E and 5E adventures have similar ones.
A lot of the Adventures of Faerun mini adventures often have them as well.
I'm handing out less thanAD&D and BG3 but probably more than ENworld would. Fairly close to DMG guidelines. Sometimes I do drop a legendary tier two.
Magical weapons usually go +1 ir 2, extra dice of damage, very rare or legendary towards the end. If a legendary drops early (eg lvl 7) there's no upgrade.
Common items and generic +1 items are available to buy but not in unlimited quantity. I dont generally track potions of healing. You can't buy clockwork amulet en masse. +1 weapons, wands of warmage, amulet of devotion, +1 shields are generic types.
Vendors sell curated lists of items. They might have 3 eg 2 uncommon items (not +1), 1 rare. They won't be generic +1 items however. Vendors can be found in surprising places.
Very rares and above generally need to be found. A lot of items are from older editions or BG3. Rule of thumb conversion is upgrade items rarity by 1 if a weapon has an ability. A +1 shocking weapon from 3E functions the same but its rare. Probably wont require attunement as theres better ones at that rarity. A minor upgrade might require attunement eg +1 keen shocking weapon. A ×2 version would be very rare.
Similar deal with 4E items. Compare to existing items go from there. Minor ability no attunement. Medium ability attunement. Major item kick it up a rarity.
So thats where I am atm. Trying to avoid the following.
1. Magic item Christmas tree.
2. Magic item supermarkets.
3. Excessive min/maxing.
4. Boosting exploration and social. Eg finding vendors, convincing them to sell. Contacts and sidequests.
5. Guaranteeing basic items are available.
6. Avoiding stacking abuse with non attunement items. No you cant buy 10 clockwork amulet.
7. Magic item supermarkets in essence obsolete 90% of magic items and heavily incentive to internet theory craft. Had enough of that in 3E.
Anyway your thoughts on frequency, power levels etc of items?
I avoid giving out +1 etc. items that aren't attunement, because I find PC's to-hits and ACs get very high with them. We know that 5e's math is based on no magic items- so adding those +'s starts to add up. And I have players that are very heavy on the optimization front... they don't need help from me to stack their bonuses so high that it gets kind of silly.
If you do want magic items for sale, but don't want "shops," I'd recommend using Xanathar's Guide's buying & selling magic item downtime activities. It makes it a time and gold-sink, and there can always be complications- but you do need to make sure players know that there are other things they can spend gold on, like strongholds, organizations, etc. otherwise the
only thing that they see gold for is magic items, like in a video game. I use A5E strongholds and MCDM's Strongholds & Followers frequently.
I
do make it easy-ish to buy consumable items, like healing potions and low-level scrolls, depending on the area.
I think by partway through tier 2, each character in my game has a rare or very rare magic item, and a few uncommon items. I'm stingy with magic early on, but once we get to tier 2 they seem to crop up more often. But since I use level up A5E, something like +1 Full Plate is categorized as Very Rare. and it'll be an attunement item; +1 plate, with some other magic effects. I don't like having just plain "+1 longsword" anymore- I try to inject some flavor with the effects and names of my items.
edit: I'll also note that as characters get more and more features added (hi A5E), the cognitive load for players becomes heavier and magic items just seem to add to that load. Players have trouble remembering every feature their characters have available to them (hi A5E <3 ) and magic items that do more than "+1 sword that can cast burning hands 3/day" aren't as desirable as they once were. The "engaging mechanics for PCs" have slowly moved from the GM's purview via randomized and curated magic items, to the players' direct control and choice via more and more character features.
After all, if your character does everything you could want it to with just the features you've chosen, wouldn't your desire be items that make your those features even more effective and reliable (+to hit, dmg, DC etc)?
