What you say is true, however, there are other factors here.

Of the two rotations I mentioned (not the HS one, I mean the to IR or not to IR one), the main difference is...

More cooldown stacking in way 2 (no IR for first DoTs) vs IR for first dots + possible BL procs.

I haven't had time to figure out which one is better, also keep in mind BL procs push back your CD's, further complicating how well you can stack them.

Granted stacking them does not really matter, except for having them all up for all of Barrage.

Is losing IR for barrage worth having IR up for 3 more ticks of DoTs/BL? Someone will have to check if so. Again the difference is small, but obviously as we're trying to optimize it is a point to consider.

I prefer the second simply because since it is easier to stack cooldowns, and all of them are up for Barrage.

Furthermore with the first rotation, I don't know if it is worth the wasted GCDs (which could be HS) to reapply dots as IR expires.