User blog comment:YourPrivateNightmare/Hail the hourglass!/@comment-6526049-20130915151659/@comment-5077844-20130916052211

In that sense, GA would be preferable over Hourglass at APCs too.

And, ironically, the example you just mentioned, Lux, gives you a big enough timeframe to react since her ult has the characteristic sound and visual effects before it fires. I'd consider it quite likely that any decent player can block a Lux ult by simply pressing keys 1-6 (i mean I managed to block on of those with and hewr ult, it ain't that hard)