4 cups (568 grams) works well because it’s enough nuts to allow the blades in the high speed blender or food processor to do its job. Less nuts, and you won’t be able to effectively use your tamper to work the nuts toward the blades in your blender, and your food processor may push a small amount of nuts to the side without having the chance to blend them down properly. You'll need a rubber spatula to scrape down the sides of the bowl of a food processor or high-powered blender.