It's not just moisture sensing. Modern dryers also use patterns to prevent shrinking in terms of reducing the heat and then bringing it back as opposed to a constant temperature until dry.
Unless the load is very small this doesn't really do much - water evaporates and uses however much heat the dryer can put out. It is only near the end of the cycle where this can make a difference in most cases.
The whole point is that the amount of heat the dryer puts out goes to zero/very low amount for a period of time. So the evaporation stops and the cloth I guess has some time to make smaller adjustments? Then the heat resumes. I don't understand why it works, but I do know modern dryers do it.
