AMARC has different levels of storage. Some planes that are just parked for a while are kept up for an easy return to flight. Once an airframe is surplus to the needs of the US military, it is parted out as the demand for parts calls for. Or it may be saved for a foreign user. At some point when most of the good parts have been removed, the scrappers are called and it's carved up.

At the begining of SALT, the planes had to sit for x amount of days after the wings came off for the Russians to get a good picture.

The sad photos are the ones from Walnut Ridge, Kingman, Goodyear, et al at the end of WWII. B32s going straight from the factory to the smelter with 2 hours total time. If someone just had a large hangar back then...