I use my 16' awning whenever I am setup, especially during the FL rainy season. I set the rear end of the awning lower so it is at an angle and the rain runs off near the back of trailer.
Rain is one of the main reasons that I use it. I do tie it down to the ground with the spiral tie downs that are about 18" long and don't put it in unless a hurricane is forecasted, which I wouldn't be in the RV anyway... It has survived many of our typical afternoon thunder storms though.
Have I just been lucky? Perhaps, however shade and rain are why I want an awning...
Edit:
This type of tie down