Solo'Que and Main a Role

High Tier players, what I have read so far, likely say that sticking to a role and becoming the greatest at that one role is always the best way to rank and climb elo quickly since you have that one role or champ locked in. So basically you are unstoppable with that champ. I went back and found one of my favorites champs to do this with, Katarina. And well.. http://i.imgur.com/oDhHt4U.png. It worked out. I got mid all this time, always putting Mid as my first option then Top as my second, knowing that Top is (I think) the second longest wait que for a game.** THEN** after my whole win spree I get Top.. so awesome, I kindly ask the person who did get Mid if we could switch.. No, of course. I go on to lose the game because the enemy mid lane, a.k.a. went out of control.

         **SOO**, how is it that we get these tips to focus on a lane or champ to win and climb elo faster when, in reality we never are granted the lane or champ we desire to play to rank through solo que? Really trying my best to get Gold 5 before the end of the season, currently S1.