I have been doing that forever at 5000 mile (or less) intervals. It not only insures a dry pneumatic system is it a complete evaluation of the functionality of the air system check valves and protection valves.
If you have been servicing the air dryer regularly you should never ever see a drop of moisture any where in the system
Jon and Di 2006 Liberty Elegant Lady, 2021
Jeep Grand Cherokee, 1950 Ford
Knoxville, TN
Owner of three Liberty Coaches since 1990