I have a watchman in my 24 gallon nano. He will chase food about 6 inches or so from his hole, but that is about it. I use the sinking pellets and drop it in the filter overflow and that knocks it everywhere. I only feed the tank once a week or so, I have pods
on the live rock that keep him very fat and happy. Do you have any live rock in the tank? If you have a lot of it with stuff growing on it, he will eat that stuff first and foremost, and I would not worry too much about target feeding him. I would use a sinking pellet rather than flake food, however.