We have three different teams within the champion team overall, which often means that we have 3 new champions in testing. That may change over time. You are correct that internal playtests can quickly get out of hand, if different teams want us to try out several new champions, several champion updates, some item changes, and maybe a clarity change all in the same game. You have to be pretty careful to get the most out of playtesting and try not to test too much or too little at one time.
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