In my opinion, don't care about the number and speed of jumping, it is only useful to jump as long as possible. You may only jump for one minute at first, but you can add 1 to 2 minutes each time in two days. Step by step, skipping rope is very good for your health. When you can jump for 30 minutes at a time, the effect is equivalent to jogging for 90 minutes, and you don't want to jog like that, which will lead to the risk of joint wear.
Of course, skipping rope also needs attention. Beginners and mildly obese people should jump on both feet. When jumping, the heel should not touch the ground, the toes should touch the ground, and the knees should bend slightly to cushion when touching the ground. If you have any additional questions, you'd better talk about your physical condition, because extremely obese people are not suitable for skipping rope and are easy to get hurt.