The most common call from this area is a single panel that's bowed or cracked, usually on the section that takes the most sun over the course of a day. Arizona heat is hard on foam-backed panels specifically: the steel or aluminum skin expands and contracts more than the foam core underneath it, and after enough summers that mismatch shows up as a bulge, a crack along a seam, or a panel that no longer sits flush against its neighbors.
A close second is impact damage - a panel dented from a bike, a trailer hitch, or a mower thrown against the door - where the rest of the door is fine and there's no reason to touch anything but the one section.
What we don't usually see much of here, compared to older parts of the service area, is rust-through or rot at the bottom panel, since the housing stock is newer and the doors haven't had decades to corrode. That's one advantage of a town built mostly in one era - the failure modes are more predictable, even if the parts aren't always easy to find.