When to winterize in the SW

I do not consider it winterizing since I do it summer and winter. All I ever do is drain the fresh and blow air through the water lines. I also drain the black and grey. I do that any time I will not be using the RV for a few weeks. Doesn't take long and keeps things from going sour. The P-traps will get some antifreeze if it is going to be below 20 degrees for several hours, but that is generally not until Jan or Feb.

Never had a pipe freeze on the RV although I did have a few sprinkler heads freeze in the yard.