the only ulduar that matters is one with hard moad and algalon, so gtfo.
once you can prove to me that they one shot every boss on hard mode and do it in an hour and fifteen minutes i will believe you. honestly, lets figure some math here. there is 14 bosses in ulduar. of those 14 bosses, there is trash on the way to the bosses. figuring the dps isn't mattering on flame leviathan because its easy mode it still takes ~5 minutes to get to the boss. lets say everyone keeps 1- stacks up. thats a 3 min kill. ok, you got 67 minutes left. moving to xt next, you rebuff, and regain mana. ~1 minute. clearing that trash is another, and we won't even count readychecks. XT will take around 3-4 minutes to kill, and that is relative because if you can do it in an hour, you will do hard modes. there isn't another heart phase and you spend time running from light bombs and AoE adds. all in all around 6 minutes left. you have just spent 15 minutes doing 2 bosses. since there are 60 minutes in an hour, and 4 x 15 = 60, you can figure that you will only be able to do 11 out of the 15 bosses, max. plus ulduar isn't a clear until algalon is down.