I have rattled in bucks from about now until the middle of November. Don't give up on it. When it works, it works well, but it is not a 100% fool proof works every time tactic. I would have to say overall, in 25 plus years of doing it, it has worked about 15% of the time I have tried it. I have probably had the best luck with it mid-day or right before dark. However, I am sure that is due in large part to the areas that I hunt.
I have only used a grunt call to turn a deer my direction. I have never called one with a grunt call that I had not already seen moving through the area.
Dirty Steve
I have never had luck rattling deer in. A few years ago I got to watch 2 mature bucks fight that commotion drew in 2 additional bucks. So I know they respond to it.