Now, if you want to be competitive, then you probably should, at least in large schools I am guessing.
If you want to pull back and rehearse less, have more efficient rehearsals, then get after it! There will always be people who work a ton, expect a ton out of their kids, and feel that more hours are what it takes to get it done. There will also be those that prefer quality over quantity in the amount of time spent rehearsing.
I don't think that changing a rule to keep people from working hard to be successful has any value when you can already chose not to do all of those things.
You do you and what is best for YOUR kids, and let someone else do the same. Some would probably do more than 8 hours (which is why there is a rule in the first place) and that is what is good for them and their program, then so be it. Work your tail off and do the best you can with what you feel is right for your situation.