Has Riot ever sent out a survey asking about game balance and game time?

Honestly, doesn't seem like a bad idea in my opinion. I think it would give them a good look into what people think of the current state of the game as opposed to asking if they enjoyed their last match.

They'd be able to see if people do genuinely believe games should be longer by 5 or 10 minutes, or if they should keep it how it is with on average 25 or 30 minutes. It would also give them a good look on multiple opinions on why people think the game is unbalanced in the current meta.