None of the anthology books have Tier 3 adventures. Candlekeep’s Level 16 one is the ceiling.
Waterdeep: Dungeon of the Mad Mage touts itself as going up to level 20. It actually covers levels 5-17, and then there’s one more dungeon level after that wherein the book kinda throws up its hands and says “maybe they’ll go up three more levels during this last part. I don’t know; who knows? See what happens.”
I think Vecna: Eve of Ruin is the only official adventure content published by WotC in the past 16 years that legit goes to level 20.
Personally, it takes me 2-3 years to get campaigns to levels 11-13 and by that time it does feel like time to start a new one, not keep going higher than that.
				
			Waterdeep: Dungeon of the Mad Mage touts itself as going up to level 20. It actually covers levels 5-17, and then there’s one more dungeon level after that wherein the book kinda throws up its hands and says “maybe they’ll go up three more levels during this last part. I don’t know; who knows? See what happens.”
I think Vecna: Eve of Ruin is the only official adventure content published by WotC in the past 16 years that legit goes to level 20.
Personally, it takes me 2-3 years to get campaigns to levels 11-13 and by that time it does feel like time to start a new one, not keep going higher than that.