Last time I used this on Android, there were 9 points but I couldn't use any one more than once. You can double back in a very limited way, but the more complex

Last time I used this on Android, there were 9 points but I couldn't use any one more than once. You can double back in a very limited way, but the more complex patterns I wanted to use were impossible. I'm sure there's more written on this, but most patterns I've seen are just way too short. And hug the outer edge, are in-order, etc.