Even if the likelihood of getting assigned a trip goes down after the 9th hour, it certainly doesnt absolve you of the SC obligation.
The new practice eliminates my leash 3 hours early. Thats 3 hours less of sitting in good cell coverage, 3 hours earlier I get to commute home or exit my 2 hr radius of base, 3 hours sooner I can enjoy a football game without my kiddie straw, 3 hours less I have to drive around with a suitcase in my trunk.
Everything isn't win-lose.
Enjoy a good thing!