The car is always garaged and I live in Fla so no freezing weather
The dealer has recommended a brake fluid change at 20,000 miles. on 2008 Volkswagen Beetle
You can but, it really isn't neccessary. Just check the color of the fluid every now and then. When it changes to dark brown in color then replace it. It starts as a light yellow to clear in color.
it could need it only if there is moisture in brake fluid or was contaminated with something else, or is very dark