I really thing this kind of system could be put into the game for mentors.
Taking place of the mentor roulette, you'd receive notifications that a duty currently requires your rôle and ask if you want to join it.
You could say no to those notifications, and they wouldn't even appaer if you're in a role that can't join a duty or already in queue for something.

However, refusing too much notifications each week would temporarily strip you of your mentor status. And mentors should have some QoL as an incentive to keep their status, like a bigger saddlebag, or cheaper teleport, etc...