Mostly it depends on how much they're exposed to sun. (paint will fade in the sun too)
If you drive it occasionally and garage it and it's applied correctly, the vinal will last almost forever.
I have the origional paint on the 71 Mach1 and the vinal tail stripe and Mach1 logos still looks great, no cracking at all, no pealing, only very slight fade in 38 years.

The wide over the top Shelby strips, I would paint for sure. But the side stripes don't see as much direct sun, go vinal.