I recently started progression in heroics and already my guild is haven't issues with progression. Its not the challenge of a new boss, but its our own raid leader. You see, he keeps jumping from boss to boss before we have Time to learn the mechanics well enough to get a kill. We even managed to get 1 boss to enrage, but instead of keeping up with it and switching up the strat, we immediately moved on.
During the start of Cata, I had similar issues with my old guild. When there were 3 raids to try, we were finding progression very slow. On more then one occasion we would go a whole raid week without getting a boss down. The problem was again, we kept jumping around from boss to boss. Once our gm had enough and told the raid leader to focus on one, we found steady progression and managed to get more bosses down in one week then we had in the month before.
Now we are going into WoD with the devs wanting raids to be less linear so we can pick and choose where we go and when. I for one an opposed to this. Sure, its fun and is very nice. I like it over all. However, the problem comes when guilds have issues with progression on one so they move to another. They could also be spending too much time trying to learn 2-3 bosses all at once to not be spending enough time killing one. So I am just wandering if anyone else is dreading a raid with a lot of choices in which direction you go. Mostly because some guilds will bounce around too much to make real progress.