I keep Magnifica, Haddoni, Malu and Gigantea for many years. I keep other species too but these four are my favorites. Good clean water condition (nitrates and phosphate not detectable by hobby test kits) and appropriate amount of current for the species keep them looking their best. Feeding or not really depends on if I want them to grow. If I am happy with the size of the anemone, where they are, I don't spot feed them. If this is the case they grow very slowly. Otherwise, I feed them every 3rd day or so. I have got Gigantea for 4-5 inches size to 16 inches in 8 months with feeding.
There is no question that feeding anemones will get them to grow faster. I chose every 3 days because when my anemone happen to eat one of the medium size fish, they regurgitate the cleaned bone in 2 days or so. This is, IMO, sign that they finish digesting the fish. It really does not mater how often we feed if we feed small food. However, if the food is sizable, it will take time to process.
I don't have any study to back up what I do, but I spend a lot of time observing my animals. What I do is reasonable and certainly works. While it may not be the fastest way to grow anemone, they certainly seem healthy and grow well when I want them to. I am not in a race to see how fast I can grow my animal.
Given appropriate condition for the species, not feeding is fine. A veteran reefer will not be able to tell if my anemone have been feed regularly or no spot feed for years.
Two of my Giganteas
Magnifica and Gigantea