Twitch's ult should increase duration with points put into it
ult lasts 12s at max rank, and gains more AD than Twitch.
gets 15s, a short range increase, and a shit ton more AD.
gets his range increase and %dmg every 10~ seconds.
gets her rocket range and bonus AD any time she wants! (provided she has mana)
I'm not saying these champs are op, I'm not discussing their balance at all. My point is that the fun to be had with these champs is had while these modes are active. Twitch gets a measly 5 seconds and it's not enough time to work with! The only thing Twitch gains from putting a point into his ult is the bonus AD increasing by 10. All these other champs get that extra damage, along with shorter cooldown, longer duration, or a range increase to boot!
The bottom line is: Spray and Pray's duration should either be reverted to 7 seconds at all ranks, or increase from 5/7/9 seconds based on rank.