Most dungeons take around 20ish minutes to get through. Making bigger pulls does not do much if you party lacks key skills that burn down mobs more quickly. It's always going to come down to party composition and tanks will read that better than healers or DPS.

I remember a Sirensong party that could barely manage a pack of three mobs. DRG, BRD and WHM. They skipped learning some skills or perhaps story skipped as friends to that point. If that three-pack took an eternity, imagine pulling six or more! Whole run was just painful. Took 30 mins.

And time slows for tanks harder than DPS or healers. You know a group is just bad when a boss rotates through their attack script three or four times.

Even if the tank is bad or legitimately too conservative on pulls, kicking them means waiting on a new tank, adding to time you could be finishing said dungeon. Did you want this done quickly or just want to control what others do. Not all tanks set their search to join "in progress" because there's this superstitious notion the group left behind is bad where that usually is not true.

When you roulette, you shouldn't be expecting absolute perfection. If you want something fast and consistent, go with a premade group. Don't impose on random players. Most people want things done fast, but accept others may be learning or have different comfort zones.