If your doing it according to readings on Westside, then it depends.
Those new to the system are best off using the same exercise for DE, but changing up the type of wave. Like a 3 week lactic acid tolerance wave followed by a three week free weight wave (use around 10% more bar weight when using free weight), followed by a 3 week wave with bands. That's not to say there's anything wrong with sticking to the basic wave for multiple waves.
For those that are more advanced, they might change the exercise and/or amount/type of accommodating resistance for DE every week.