If you have a dummy you can use this time to develop a crushing choke. When you are training with a live partner you can never full out squeeze and crush their neck and/or jaw for an extended period of time. If your choke is set once you start to squeeze they will tap or go to sleep relatively quickly.
With a dummy you can squeeze and crush it for as long as you can and want to. To develop strength and endurance you have to be able to maximize the use of your muscles over time. Well, you have the time and you can easily have the training equipment to develop that crushing choke.