You see someone familiar, perhaps on a TV show or as an extra. You realize it's an actor or actress your previously worked with six months or so ago. You text them to congratulate them. "Uhm...Who is this?" Hmph. So how long do you hang on to people's numbers in your cellphone? Six months? A year? Three years? What if the most interaction you've had during that time, might be Facebook like or possibly no interaction at all since the end of production? Just wondering what the consensus is.