Its like a car, you don't keep pressing the accelerator further and further to travel down the road. You find the optimum location to maintain a safe speed. If something changes, like the road turns, you adjust the accelerator until you are once again safe. If you stayed static, you'd probably fly into a ditch. If you are unnecessarily pumping the pedal, your speed would oscillate unpredictably, and any number of consequences would occur.
Its like a car, you don't keep pressing the accelerator further and further to travel down the road. You find the optimum location to maintain a safe speed. If something changes, like the road turns, you adjust the accelerator until you are once again safe. If you stayed static, you'd probably fly into a ditch. If you are unnecessarily pumping the pedal, your speed would oscillate unpredictably, and any number of consequences would occur.