I've been abusing this ever since the new matchmaking rolled out. This is all you have to do; instead of actually picking your secondary role, just pick mid and behold as every game you receive your primary role. And even if by some miracle you're stuck with mid, trade it off, chances are that someone on your team is an autofilled mid main.
Can confirm. Maybe it's overkill but I queue support/mid and get support 100% of the time. It's OP effective.
I am otp jungle. I pick mid secondary and reset Queue after 1:30 since years. I get main role every game! 100%
For other roles and regions you may need to reset queue earlier.
Lol you discovered rito's top secret
I just go whatever lane I want /support and get it 90% of the time. Last season I played like 9 out of 10 games on mid while queing mid/support.
Unfortunately yeah :(
Half of the community Main 
which makes the Role really popular
and if those champions are banned , they just pick anything and feed , So always pray that your mid laner doesn't main them
and always pray that your Jungler isn't a Mid main that will pick 
and power farm the whole game
