Total number of champions

It's been a concern of mine for a while now that League keeps adding champions. My concern is pretty much the amount of time required to keep current or get up to speed (for new players). Every patch means one should test each champion changed (or at least those greatly affected by the patch). On top of that, a new champion means a few games (at least?) to see how they play out. For a new player, that currently means getting to know 136 champions. That would take over a year for most people considering the amount of time per day they could put in (along with learning how the game works overall). I don't want to suggest putting an end to the creativity of new champions, but, every champion you go up against for the first time (or play for the first time) is a learning experience, which means you can't compete as well with someone who knows your champ and theirs. Instead, I suggest that League starts a rotation of available champions that can be played that expands as you move up in rank (maybe Bronze is limited to 30 champs, up to all champs at Master/Challenger). This would balance the time people invest with the amount of knowledge required. The rotation could be distributed by role (the specific ones like juggernaut / crit marksmen / etc) so the experience of playing doesn't change that greatly. The benefit for Riot is that it's much easier to keep track of how a smaller pool of champions work with each thing changed and it eliminates the need for an overall cap for the number of champions (there's a point where there's more champs than you can keep current on, even if you play 16/7). I'm kind of curious as to what people think about this, so please comment if you have any thoughts on the subject.