To answer your questions well. the answer is "Sometimes" I suspect.
Now if you order a NEW factory built RV it is often delivered TO THE DEALER "Dry" that is no water is, or has ever been, in the tanks or plumbing, This is the ultimite "Winterization" The Dealer may add water and test the plumbing, fixing any detected leaks (one hopes) or not Depending on the dealer and the timen of year.
USED RV's the dealer may winterize if it gets cold.. Or not, in which case damage can happen.
I just fixed my 4th plumbing leak on this unit, the first was due to freezing, this one may have been a 10 year delayed same freeze (An elbow cracked, the line had two elbows one on each end, this last leak was the other end of the same line) all new nice shiny brass now instead of plastic. Do not anticipate anyh more leaking.
Other leaks were kitchen related.
