I have had times when using a decoy resulted in the tom coming in like I had him on a rope and other times see them putt and go the other way real fast. Normally on an ambush set up I don't use them. Roosted birds often go the same way every day. Sometimes it might take a few days to cut the possibilities down but as long as you aren't busted that tactic remains pretty productive. I never call to the tom when he is in the tree. Setting him off often can often bring in other hunters in addition to spooking him.