I am thinking of having it available if/when all Disciplines are down. For example, I got really lucky in Mearatas recently and had 3 named up at one time. The Center Mob and two Ancient Wardens. I popped my glyph of dragon scales on the tank, which lasts 4 minutes, and proceeded to smack them all down in quick succession. The first went down quickly, the second a little slower and the 3rd felt like forever. I then recognized that both zerkers had blown through all their discs and was waiting on Disconcerting Discipline to come back up (granted its only down 3 minutes)
The same issue applies when I am farming Contract of War. I will clear all the trash mobs, then kill the named by the bridge, then the one on the hill and lastly in the middle circle, all while glyph of dragon scales is active. Granted, it usually fades while fighting the last named.
I freely admit your plugin has made me zerker lazy to where I almost forgot how to play one and I am having to look up their CA's to find a good spot for it to go. Regarding stacking, if used with Savage Spirit, you just wasted 40AA, since Savage Spirit is a 285% non-cumulative increase to your melee attacks and Glyph of Destruction is 60%. If memory serves me correctly, it does not stack with a vast majority of CA's, if not all of them. This occurred in the middle of 2018, when DBG, changed the cost of Glyph from 5 AA to 40. I will do some research or hopefully some Zerker Guru will chime in and provide their input or call me a booger chomping moron and leave it alone as this plugin is AWESOME.