i'd be ok with keeping it 7, but adjusting the numbers so that less fighters get the minimum or close to minimum times. shift the bell curve toward longer careers but still have the possibility of shitty early retirements.
Personally I like it the way it is now. I have just been absolutely sodomized by early retirements. It pissed me off. But we are all in the same boat and it makes you appreciate the guys who have a long career even more.