I guess that can be a difference in strategy. The way we do is that one tank (me) takes 5-6 stacks on the pull before we first switch. By this time, every dps is either mutated and finishing of their 5th stack. So they are already turning on the boss. So by that time its just my job to go on a seek and destroy finding myself 5 adds to kill myself asap to get my own mutation. Its a waste of the other dpsers dps to help me get my mutation, so as soon as they got theirs they are on the boss, there are no welfare mutations for me to pick up.
We keep the adds clean until that point so I do not have a huge AoE pool of adds to pick up. Basically, this is the point where we start kiting the boss in a circle. So I have to take my adds 1 by 1.
I am not saying that the blobs does not proc BH, just saying that the nature of your rotation will proc extremely low and few BHs.
As on blob usually goes like.
Running towards the blob -> J + AS before reaching the block -> Reach the blob -> CS to proc nature damage and by this time either HW or HoW to finnish it off.
So on each blob you are only really using 1 CS. Remember that J, AS, HW and HoW do not proc BH. So the amount of your damage that actually procs BH on a blob is insanely low, especially due to do nature damage proc that you get from the boss. You will actually do more BH healing by switching to SotR to kill your adds faster to get back to boss faster with SoI.
Though, if you have a tactic that allows you to get instantly mutated, fine, then you do not need to switch. Since that negates the point of switching, which is to kill your adds faster to get mutated faster.