In my experience the tug is only needed if they're known to not eat the food after constricting. For instance our big pinstripe girl will constrict and then abandon her food. She's been doing this for the past couple months. I realized last night I had been forgetting to wiggle the rat as she constricted. Last night she ate it for the first time in over a month, maybe because I was tugging on the rat for 30 seconds, or maybe she was just finally hungry. Who knows! (: