It depends on the gecko and the nutritional value of the worm. I don't usually count so much as just try to keep geckos at what I consider to be their optimum. I like my geckos to have a tail that is thicker than the body, but not by much. I like them to appear bright and have a normal amount of fat deposited on the actual body (not too much, not too little). I keep my really easy keepers 10 mealies (well gutloaded, fat, and dusted) a couple times a week. If I see their body condition change, I adjust their feeding accordingly. If they start to get fat, I reduce the number of feedings and if they start to drop weight I increase it. Some geckos just require a lot more food than others. I have one male that I can barely feed without him getting way too fat.