I transferred back to my old guild five weeks ago and in my first raid with them, they got 3d down for the first time. Since then we have gotten 3s twice, and settled for 2d twice, so I think I can really speak to this.

We are all committed to doing 3d. We will usually run about 20 attempts at it before we give up. Last night our first attempt was very strong, and we had about an hour of good attempts, but with a brand new-to-the-guild tank who had never MT'd it before, it took awhile for everything to shake out properly. But when it did we had zero deaths in the raid.

Nights where we have failed the raid lacked focus, lots of people would die to death spots, adds, flame waves, whatever, just carelessness/tiredness. Also on those nights it seemed like our DPS wasn't popping like it was on successful nights.

To sum up, the whole raid must commit to at least 2 hours of attempts, and you can gauge whether you should spend that time based on how fast stuff is dying, and how well people can survive. I.e. first drake should be dead within 15 seconds of second drake landing if not sooner. Raid has to be skilled enough to stay alive, geared enough to do eet.