Not sure how challengers work

This is my first time really being into challengers and watching all the matches (rankers are insane). But what confuses me about it is after stage one they make stage 2, than the winner of stage 2 goes to ascension. But that's only 2 events. So your telling me there are only 2 events in NA challengers all year? Can someone provide some more clear info on this because it doesn't make sense to me.

i mean its pretty much like franchising, except it doesnt have an international
regular season - playoffs - regular season - playoffs - ascension
last year challengers had a third split tho idk if there will be this year