Also, on a metallic painted surface, the decals can sometimes crack and lift at the edges after time, if not sealed with a clear coat. This can be measured in months, or years !
I have a 1/48th scale B-17, built around 24 years ago, where the upper wing decals are starting to crack at the edges, although those on the NMF fuselage and the red-painted fin are fine, as they were clear-coated. Close inspection shows I must have forgotten to clear coat the two wing decals !