I think my personal minimum score for anything I'm thinking about doing--knitting or not--is about a seven on the interest scale. If something's scoring a five, like a movie, then I need to add at least two points of knitting to do it for me to be able to hang in.
If it's something gripping, like a conversation with a charming and entertaining friend, I may not need to add much knitting at all. If my friend scores a nine, I might only toss in a plain sock, with no patterning or anything, just round and round on autopilot while we visit. (I can only think of one thing I do with another person that really has no room to add any sort of knitting to, but let's not discuss it here.)
