I don't know if this suggestion has been made before. Even tho I'm not a Sensei, I would like to suggest something. I think admins should grant Senseis the ability to open/close their own threads, as people keep on posting in the application threads even tho the applications are full and Senseis may sometimes even forget to reply to one of the App thread posters. Sure, Senseis may ask mods for it, but bugging mods everytime for it doesn't feel convenient. This one feature would enable Senseis to easily see whom to accept/whom not to accept.
Edit: If Senseis misuse this feature, then it can be revoked from them.