Since I couldn't find something concerning this topic and thinking it isn't really a bug I like to address it here. The 30 seconds timer for calming the mobs is ridiculous short in comparison to the cool down of exact same durance. I'm not counting the times my toons got killed while waiting for the cool down to end when the calmed down mob awakens again. Dear Devs, please change either the timer for the cool down or for the calming. 30 seconds for both isn't ok.
Yes, it is still slow going, but with 2 different items to alternate, you can leapfrog even if the random placement of which ones are aggro is a bit tight.