Sounds like you are on the right track,and you cant always tell where they are going to came from,I have snuck in and set up on a feild edge got ready and started calling and have one stand up in the feild,where he was laying sunning about 200 yards across the feild in about knee high grass.I would have give you ten to one odds that he would have came from this thicket in a low lying area beside the field on the oppisite end from where he was,but I would have loss that one,and they will sometimes get behind you and do the flyby at 100mph and not much you can do to stop it from happening,you can sometimes get a backend shot and kill them.Good Luck!!