The experiences on PC are so varied it makes me wonder what is going on. Sunday, I again had to play a multiplayer match to get quests done and it popped quickly (less than 30 seconds) and put me in a full lobby for TT-I was on plants and it was Zomburbia, we got to the final point before the end minigame and lost there but it was a great time, I got my 'shoot down a pirate parrot' quest done, and got some vanquishes as a sunflower. This was fairly early, around 9 AM Sunday morning central US time.
I've been in really empty lobbies as well, but it appears that what happens in those cases is that I'm in the overflow lobby as the match(es) are currently full. Only TT and possibly the portal events, are active in my experience but I've never had a big issue getting matches barring errors and getting kicked into that overflow lobby.
And again, no cheaters in that match, although they are definitely out there. NA East as usual for server for me.