That depends on your cham. Size, age, eating habits. When my male was 3-6 months old, he could eat a dozen crickets every day. Now that he is a year old. He doesnt eat much at all. But I also offer more types now. But my females are eating machines. They will eat 8 insects or so everyday. But all my males are more picky. It all depends on the individual I think. I dont think there is a "Must eat this much a day rule". Just let them eat till they are full.