Unpopular Opinion: Regardless of game length, I've had some good matches
Idk if it's because I went 7-3 or it's because of my elo range, but I had some pretty intense matches so far during my placements. Even when I shat the bed against Alistar, I came back after laning phase both times. Even when it felt like we were set to win, my top lane fed and we lost. We had a stomp or two. We had a game where we got stomped. There was a wide range of different types of games, and a good bit of them felt pretty intense and satisfying to play. Many of my games ended by around 25 minutes, but I didn't feel like they were lesser quality games because of that in these cases. Shorter? Yeah, but still good games. Of course, I had a few games that made it to 30+, too...but only like 3/10 of them.
I think the tripping over game length is...somewhat warranted, but also used as an excuse for playing poorly.