You really need therapy about this chip dilemma mate. Hasn't this been discussed before?
viewtopic.php?f=5&t=416viewtopic.php?f=5&t=279But, in short, yes, in my view they are a load of bollocks. Particularly the type of chips that are so popular.
Overall, there really only appears to be two situations where chipping would occur. If a surface is violently struck, or if the painted material has been poorly primed, as in the alloy elevation housing on the Flak 38 in the second link above.
Wear would be the far more realistic form of 'weathering' to depict. In my mind, the best way to understand appropriate wear is to ask what is the surface made of, what is it used for and how often, what is the likelihood of it coming into contact with other objects and how etc etc.
As Roy pointed out in the first link above, many of these vehicles would never see a combat life that would bring it anywhere near an age where the elements would have such a structural impact. Also, as he pointed out, operational vehicles were well cared for and maintained.
Allan