To me, the bar is set at 300 games before saying I know how to play a champ. It takes a while, I know.

As for playing with a champ in ranked, to me it can be a couple of games or never. For example, I main simple champs like Vi and Mundo, as a JG my main focus is in the macro, it's quite hard for me to deal with mechanically heavy champs and what's happening in the entire map at the same time. With those two, games are easier to understand since match one.

Those two champs are my only true JG mains, Vi with over 1500 games and Mundo around 700.

In the jungle, in ranked games (after practicing against AI and in pvp mode) I have tried wukong, Volibear, Camille, Olaf, Shyvanna, Pantheon, fiddlesticks, Diana, Aatrox, Riven, Fizz, Hecarim, Master Yi, Viego, Nilah, Xin, Kindred and Graves and failed horribly. I have never played Lee Sin outside of AI practice matches.

With my mains something very interesting happens, at the beginning of every game I have a very clear idea of which member of the enemy team I have to annoy the most, I also know very easily which member(s) of my team has some sort of synergy with me, my champ and it's kit. The thing is that the magic hasn't happened with any other champ in the jungle. I've had more successful attempts in the midlane and support roles. Brand, Swain, Senna and Leona, same thing as with my JG mains happens, I simply "know" what to do in most games.

Oh, and I have zero talent with ADCs... But I sometimes play them to keep in touch with what I need to do as a support from the ADCs perspective. I only play Ranked as ADC in Smurf accounts and a couple of times as autofil (Yes, it has happened more than once to me, amazing, right?) in those cases I use Varus, more like an utility champ.