ah, yes when making it on paper it's easy to just faff with them to get the most sensible shape and size. However, in my personal experience it makes for more stable hedrons to have the last face with some tabs on - it also makes it easier to stick because you can poke them down and they hold it in place without you having to sit there holding it in place ;). Of course, I've been using construction paper, and not card. That might make a difference.