In the five years I spent as an Armor Officer and the 25 years I spent as a Chemical Officer I never saw anyone paint anything beyond the base coat of green under the fenders. Suprisingly, the paint doesn't wear as heavily there as it does above the fenders, probably for two reasons--it's either covered in dirt or it's washed off on the wash rack. I also have to chuckle every time I see a post about masking stuff-- we used grease from a round 5 gallon can to mask headlights, inspection ports, IR lenses, cat eyes and tailights. Nobody "masked off" roadwheels-- they were just careful with the paint gun. There's not enough masking tape available in the average unit to do that-- we'd save tape for stuff like periscopes, exposed electronics, searchlights, stereographic range finders or other sensitive parts. The depot rebuild paint jobs are a different matter-- they mask, paint under fenders, etc. but a "new" vehicle coming out of depot does not stay that way long. My experience as a Chemical officer meant I served in Artillery, Infantry and with Marine Corps, Navy and Air-Force units too. All are about the same when it comes to unit painting. A caveat to this is CARC paint-- repaints were only done at depot level. I've been retired since 2006, so I can't say what they do now in the field, but I have a freind who is a Depot Commader, and he's told me not much has changed.
VR, Russ