The roasted garlic bits seem to keep tolerably in the fridge for a day or two so there isn't really any reason to roast less than a full head of garlic. Obviously you can throw some spices in if you want, but I usually just roast the garlic because I use it in heavily spiced things anyway. Don't try to roast more than two heads worth of cloves in a bunch, but naturally you can throw a bunch of pouches into the oven if you have a need for an absurd amount of roasted garlic.