A lot depends on deer numbers, habit and how long it takes deer to eat the protein. Gravity is the best way to allow deer to get feed when they need it, not when you want them to have it. If it is a supplement then they will eat it post rut or during drier times. When it rains they should back off feed. Time protein has its place for guys who have a budget or live to far from their lease/land. Depending on the timed feeder time you do control how much and when they can eat. It works better if you have good habitat to rely on. Time you feed can also dictate if you have mainly bucks vs. does eating. As far it not working as well as free choice, think of it like this: those deer eating feed are eating less from the habitat. Those other deer not eating have more habitat to eat, if you have your deer numbers under control. I have mixed corn and protein and fed it for years out of spin feeders, but you have to make sure you have some type of agitator on the spinner place to keep the feed flowing daily. If the feed bridges over then it will become a nasty mess inside the feeding from the moisture build up inside the feeder(pellets and corn have moisture, heat build up causes it to "sweat" due to feed sitting idle inside the feeder). Throwing deer pellets on the ground it wet climates is not going to work very well at all. With any feeder for protein you need a feed pen to keep hogs away.