Once your clothes are tumbling around in the dryer, there is a shutoff mechanism that stops the drying process. How each dryer handles this can make a difference in store price, energy usage, and abuse to your clothing.
Dryers offer one of two methods to determine if your clothes are dry — a thermostat or a moisture sensor. The thermostat will stop the drying cycle when the air in the dryer reaches a certain temperature. Unfortunately a thermostat does not indicate when the clothes are actually dry...they may still be quite damp or, alternately, almost fried.
A more reliable indicator is a moisture sensor, available in about 50% of the dryers on the market. It may bump up the price a tad, although you can find moisture sensors in dryers listing as low as $300. In the long run, you will save time and energy plus avoid damaging your clothing if you go with this option. The longer the clothes tumble in a hot environment, the more likely they will be damaged or suffer shrinkage. Make sure you check the machine's specifications and literature to determine if it has a moisture sensor, as it is not always obvious.
Your dryer should give you the choice of a timed dry or "more dry", "less dry" options. The best setting is half way between the "more" and "less", and then adjusting upward or downward until you have a satisfactory level of dryness. If it is ironing day, set the dial to less dry and use the dampness of the clothes to steam iron. Keeping the dial to "more dry" can waste time and energy and over dry your clothes.