I'm guessing the surrender timer is still at the 20-minute mark for PG, probably.
I would suggest to put it at around 15-minutes instead; if the game is shorter than that, there's not much point in surrendering. If the timer is shorter, there's less reason for people to even try; once surrender votes start going up, that's usually the point where other players start going AFK or just sit around telling their team why they're not going to win this fight. (had it happen plenty of times in SR, especially on games that aren't lost yet.)
Even in a case of five-support blue versus five-carry purple, there's still a small chance in playing it out to at least ten or fifteen minutes, rather than giving up entirely right from the start. (I've lost a game in TT before against triple-support, my team didn't take into account just how much sustain the three of them had over us. Eventually they all got some AP and just dominated the map.)