There’s no reason to keep doing them once you’ve cleared them. They hold very little interest.
Variant dungeons sounded cool on paper with the different paths but in reality they are repetitive: save the last “hidden” boss, it’s same bosses for every path with small mechanics variations. When you solo, it is just as easy but the adds and bosses feel like bullet sponges and the fights long for nothing. It feels that the adds are just there to slow you down. They have zero mechanics (just aoe and get out of stupid), the boss mechanics are way too simple and repetitive. They just keep repeating the same pattern over and over.