Wild thought: what if Twin Snakes (and even Demolish) had a recast timer separated from the GCD? As far as tracking the buff, it would be very easy if the buff duration was the same as the recast timer.

You called the monk rotation a priority system, which made me think of this. As monks GCD gets lower, too, weaving in oGCDs gets harder. Would it be super weird if monk had zero oGCD attacks, and instead all their attacks were weaponskills with longer than normal recast timers, and you used them as part of a priority system (except maybe Shoulder Tackle, as that's a utility move)?