Each hunter has his own tactics but I disagree with Strut and Rut. It could just be a difference between where we live though. In my area I hear tons of owls just before dark and as the sun is setting.
also many times, the toms in my area will gobble on there own right when they go to roost, or respond well right after fly up time. I actually had a similar question to this answered by Mark Scroggins on The Fever last spring. He repeated basically what strut rut said about somtimes turkeys will gobble at anything or nothing at all. He said he has been out west and they gobbled all night long. I think it just depends on the turkey and the area your in.