I totally filled it out. I told them 8 hrs, just like everyone else, knowing full well they had zero intention to follow through. I'll gladly take any opportunity to let them know my opinion on how they run their company. They stopped doing the annual survey the year after I decided to be completely honest on it.
The reason you play along is so they can't try to.blame it on us for not cooperating when they inevitably fail. Then you use that to your advantage. "Why am I over 9.5? How can you even ask me that? You promised me an 8.5 hour work day, now you are trying to tell me 10 hours of work is really only 6."