An idea to make autofill less annoying

Idea: If people play support in at least 1/5th of all their games, they get autofill protection until that number goes below exactly 20%.

Why is this an improvement over protection for last game played: Mainly because each game needs 1/5th of all players to be support. With supports being less popular than average, this would allow people to grind some games as support for their fair share and then not worry about it for awhile. Basically this gives people a little more freedom in it lets them choose to support instead of being autofilled when they don't want to. This way they've done their work as support so they are protected from auto fill. Also, if someone is planning on playing 5 games in one day, they can queue up as a support for their first match and then they won't have to worry about it for the rest of the day.

I mean non-supports still won't like having to support, but at least this way they can put their needed support games into a bank and forget about it for awhile.

Why this is good for support secondaries and mains: Are you a support secondary player who is always getting support? Would you like to play your main role more often? Well with this banking system you can go a few games in your main role without worrying about putting support as your secondary and getting it again.

For support mains who'd like to play their other role every now and then, this would let you get mid or jungle or whatever out of your system for awhile instead of being pulled into a support because of autofill despite playing 90% of your games as support.