The control is working normally when it adjusts the estimated cycle time. The time is being adjusted based on the moisture content sensed by the metal strips just inside the door. The time can jump around during the first 5 to 10 minutes of the cycle and then later on in the cycle. If the dryer is working normally and the load dries in a reasonable amount of time, then everything should be working properly even though that estimated time jumps around at the first of the cycle.
If you are encountering long dry times, I recommend that you check the exhaust vent duct system for a clog or restriction. This could prevent proper air flow through the dryer and may result in the jumping around of the estimated drying time.
If you have a long exhaust vent system you may need a service provider to clean it if you cannot do it yourself.,