Seems to me if you park a truck and don't move it for a couple of decades, the coil or leaf springs don't "go bad" or collapse. But if you drive it hard, hit bumps, tow a lot, cause the suspension to move, THAT would tend to wear out the springs.
I have a trailer made from the bed and frame of a pickup. It sits kind of high so one time I left it bottomed out with a load of dirt for about 9 months. I think it sprung up higher than it was before when it finally got unloaded. FWIW
"Courage is being scared to death and saddling up anyway." - John Wayne
.44 Special: For those who get it, no explanation is necessary. For those who don't, no explanation is possible.