These brats are perfect for a group! However, how many to cook at a time really depends on the size of your air fryer. In order to get the brat skins nice and crispy, they'll want to be in contact with the bottom of the fryer. Also, there should be at least a finger's width of space between each sausage. That being said, fit as many brats as you're able (given the space needed). If you need to make more than can be accommodated at a time, place the cooked sausages on a platter and cover with aluminum foil to keep warm until all brats are ready to be served.