Are you hunting the same spot each time? I might make a tactical move. If you have been on the same side of the roost, move to the other side, even if it is further away. If you know which way they head each morning off the roost, I might make a move in that direction, even if you have to move further away.
If you are calling at them on the roost, I would stop. I think that calling to birds on the roost makes them gobble, but reduces your chances greatly. I might do a very light tree yelp at 5:55 and shut up. Start calling with single clucks and mellow yelps when you think they are on the ground, and be prepared for a quiet approach.