The leaver penalty should be 2hr cooldown on ALL STFs. Complete the mission, fail the mission, 1hr cooldown on THAT STF...leave your comrades to suffer because you can't be bothered then you should have to wait 2hrs for the privilege of doing the same to other unsuspecting teams.
Why in the world would you want to make a buggy penalty system more severe? The hell is wrong with you people?
Not to mention a penalty existing in the first place disincentivizes new players to playing the STF's. We need those players so we get more of them, unless your all happy with playing the same 3 missions for the rest of the life of the game?