That's the thing about Hypercharge though, it may say it lasts 15 seconds, but because it acts via the turret what you're really getting out of it is a discrete number of augmented turret shots.
Currently that number is 5. Whether you use it when the fight has already started (so none of the duration is wasted), or you use it in the prepull period like in our current opener, you still get 5 shots. The reason you still get 5 shots when you use it before the pull I explained above - and if you were to do it any earlier than that (Bfb, Hypercharge, HE, RS, (pull)) for instance, you'd lose a turret shot and only get 4, so where it is now is the sweet spot.
So what I'm saying is a 20 second duration might change where that sweet spot is. If you keep it in the same spot as now you might get, let's say, 7 augmented turret shots after the patch - but maybe the timing is such that if you use it after the pull in 3.2 (so you get your first augmented turret shot instantly) you might get 8 shots, who knows? That's an increase in damage and a valuable extra extension of the vulnerability debuff, and if that was the case we'd definitely have to move its position in the opener.
Of course we know the duration and we know the turret attack delay, so in theory you could do the math and know right now - but it's something I'd like to see for myself because things can differ in practice due to latency or general combat quirkyness.
:O I just realized this might be referring to Armageddon too, if they're going to center Gauss Barrel properly that's a change I'll be very pleased in.