Repose in dungeons?

[Simaril]

I went to Qarn for the first time, and told my party it was my first visit. One of the DPS said I should stop wasting my time casting repose, and DoT them up instead. Someone kept breaking the CC as well - I'm guessing the same person ><

Do you guys use repose, dps, or both? My thought process is generally:
1: Heal
2: CC to make healing easier, and buy myself time to dps
3: DPS

I assume this is good habit, and thought process to prepare for endgame?

I guess it stuck with me because he said it with a bit more attitude, like - stop wasting our time and do something useful... which lead to me casting heal more If I felt it were a completely trivial I'd agree, but we did wipe once, and the DPS failed on the two bomb pulls. Also, another party member did use sleep a couple of times - which seems liek a completely idiotic tradeoff (DPS casting CC so the healer can DPS???). Is there a class that does better AoE damage than single target?