Originally Posted by
Seraphor
There's a Dungeon released in every patch.
Trials, Raids and Ultimates alternate between patches, and even some of those have multiple targets.
So I'd say it accounts for at least half of the content, plus anything set in the open world, which includes maps.
Besides, most people run multiple dungeons a day, via Expert and Levelling roulettes, and only run the higher level content if progging or farming, which usually isn't every day.
You can't say most content is single target just because you never run dungeons.