I feel like I can play at least a couple champs at all positions on the Rift. Support and ADC being my weakest. So I don't spend time refining my abilities at such positions or with those champs. Is knowing how to play those positions as well as the others something that will help me get out of bronze, or is this something that I should just do what I do well at. My profile I always play is Snoneper.
It's quite important. Avoids cases where people rage at you for not having a clue how to play a lane or not having a champion that you're at the very least semi-decent with.
Just make sure you have a champion that you know you won't feed in.
ADC's a special case because you have to get fed to do your job right (or just not repeatedly feed). Unless you are an Ashe ADC because you can rely on her utility and CC to help your team. Safe pick an Ashe so even if you don't get overly fed you can still be useful to your team with her slows, global vision and stun ult.
For Support Soraka or Alistar is probably the best safe picks because they aren't as difficult as a Thresh and are really good. Alistar for all the Blitzs, Threshes and Naut supports and Soraka for the passive , farm anti-poke playstyle.
If you're willing to spend only a little bit of extra time and effort you can try Thresh, works in almost every playstyle aside from a sustain comp because Thresh has no heals. Has lantern to pull your team mates out of trouble, has hook and flay for very disruptive CC and ultimate for AoE heavy slows. All round jack of all trades.
Given the upcoming changes to champ select ( http://na.leagueoflegends.com/en/site/2016-season-update/new-champ-select.html ) i'd say it's becoming a lot less important. Learning two roles is now sufficient.
Honestly, I would have to say get a passing familiarity with all the positions, for when you are last pick and one of those spots are left. That will happen more often than you would like, and you don't wanna give a free bot lane to them.
I got to diamond as a support main, my jungle stats are atrocious D:
I think it's safe to say that in at least 85% of my games I go mid.
All roles? http://i2.kym-cdn.com/photos/images/original/000/841/129/c39.png
Support Main, it's easy to climb almost all games I play are as support, with the couple exceptions of getting the unlucky jungle
I will say it's important to be able to play the role.
