Playing support should earn you Autofill protection credit

I main support more than any other role, which is fine because it's my favorite role, but sometimes I'd like to play roles that aren't support. So it's nice then that you get Autofill protection when you do end up autofilling or queueing for support, but how come it's only protected for one game? I play many, many more games as support than any other role, but in exchange I only get protected for one match. Players who play or main support should be able to accrue more than 1 game of autofill protection if they play support more frequently than any other role, otherwise you have to play support once between every single game in order to ensure that you get the roles you request. It wouldn't have to be a huge amount either, but just letting you stockpile a small amount of games where you are autofill protected would be nice.