I feed several times a day, but in small amounts. Its kinda easy to tell when my fish are hungry; geophagus root through the sand, ATF chases other fish, puffer swims up and down, danios and congo tetra nibble on the plants but dont actually eat it.
So when I see a particular fish doing whatever, I throw in a couple pellets or pieces of shrimp. I do believe in fasting them for a day or two, and then do a massive feed and clean up.
And I almost have my ATF trained on pellets, by offering no feeders or shrimp for a week. He'll take more and more pellets each time but I want him to grow so I throw in a shrimp.