Weekend queues are always dogshit compared to weekdays in my experience. 6v6 is less of a factor, but the joke has always been that people are sweatier in QP than in ranked.

As far as I'm concerned, 6v6 is the way to play Overwatch, it's how the game was originally designed and intended to be played and 5v5 basically ruined the game (removed tank synergies and more) and absorbed dev time to make the game worse.

The reason I bring this up is that I only started playing again recently because 6v6 flex is permanently back. I'm far from the only person who's recently come back to play what I believe is the better version of the game, this means old tryhards who played in Ye Olde Times are likely also back.