Maybe a mix? it's just Let's say I decide to Learn Annie Mid, most agree she's straight forward and has one of the best win buttons in the game, Tibbers. However, if we say you have to play fewer games with Annie because her kit is easy to learn; that negates my biggest issue with people taking champs they've never played before into Ranked. The matchups.
I don't care how easy a champ is, if you never faced a Cassiopeia main, a Kassadin Main, or and LeBlanc main, you're going to get stomped. Until you've faced those matchups a few times and understand Annie's Kit relative to your opponent kit.
Which is why I advocated above Silver, the minimum should be less, because I assume that these players have faced these champs at some point in their climb.
It's why I think that Champ Level is better. The less you win with the champ, the longer it will take you to get to Level 4, forcing you to play the champ more, forcing you to face not only Meta Matchups, but the off-meta.
So in Norms I play a crap ton of Teemo. I'm fairly comfy vs. his normal matchups (I'm not saying I win them, but I at least understand what I'm up against and the options available to me like Counter Builds and Rune Setups). I struggle mightily with off-meta matchups.
However, if you say you are only required to play one game if N champ us considered easy, you only have to play 1 game? To me it means they are completely clueless with the new champ. True, worse if the Champ is mechanically hard. I'm apt to say if you decide to buy Riven and want tot play her ranked? You have to get to Champ Level 5 before you can.