Legitimate Question:

[Sleigh]

A1S you should DPS full time until split, and your fair share after the split. WHM can solo heal that part in i190 while DPSing.
A2S you should DPS up until Jagd phase no ifs/ands/buts about it, at best only stopping DPS to let your co-healer get their DoTs up after you've Baned. During Jagd after everything's stabilized, get your DoTs up then let the other healer get his DoTs up. The rest of the fight is varied based on stuns and strat and who tanks what.
A3S you should mostly DPS until the tornado phase, with the random Succor/Adlo here or there. Final phase you should do whatever you're comfortable with, at the least right after the boss is back and some time after the Protean + Sluice mechanic.
A4S you should be DPSing about 70% of the fight or so. Only Jagd phase is scary.

To DPS you need a good co-healer, an Embrace spam macro, liberal E4E/Virus usage when applicable, and intimate knowledge of the fight so you know when you need to drop Cleric Stance to help out when it's a bit risky to let your co-healer solo, usually to Adlo/Succor/Indom.