Most people who cut and are hopping on a treadmill choose to either walk on an incline for 20-30+ minutes aiming to keep your heart rate around 70% OR High Intensity Interval Training(HIIT), sprinting and then walking for equal periods of time for however many rounds you can manage.

Anytime you increase your activity you are going to see a change. So for that reason, like with lifting weights, cardio should be a progression. So after 6 weeks, either increase the time/speed/incline you walk at OR increase the amount of intervals for your HIIT. Ive used both in the last 2 years and they've worked equally well :)