In three minutes you can go to your glove box, get out your Owners Manual and look in the maintenance schedule section and find out the truth. Most car makers are now posting owners manuals on the web so you may not have to get out of your chair to look it up. Don't take the dealers word for it. Don't take the quick lube shops word for it. Follow the manufacturers recommended service schedule, it is that simple.
See what the Owners Manual says about "Normal Diving Conditions" vs. "Severe Driving Conditions". There are two schedules in almost every Owners Manual. Read the manufacturer definition for extreme driving conditions carefully and you will find that a majority of people will fall into the "Severe" category. If you are not sure, go with the "Severe" schedule.
The service intervals for later model cars and trucks are getting longer due to advancements in manufacturing and fluid technologies. This is a good thing. Also, if you are not using synthetic fluids, you might consider switching for a couple of reasons. Synthetic fluids cost a little more than conventional fluids but they do not break down as fast and tend to run cooler. Additionally, synthetics are man made so there is a slight environmental advantage to using them.
Transmissions are very sensitive to the type of fluid they use, so be sure that correct fluid is being used. Any shop, whether it is a dealer, quick lube or independent, can tell you what type of fluid you need and have different formulas of Friction Modifiers to ensure you get the right mixture.