I seem to remember of the many ridiculous lawsuits of the last century, one was a complaint about the model inside the box wasn't what the artwork depicted.
Like I ever thought my aircraft carrier model would look like a painting by John Steel.
In different periods almost all companies used photos of the real model and not a box art (painting). IMHO it was not only a money problem for sure. As SaparotRob mentioned it could be some stupid lawsuit of an angry mother or granny whose son/grandson couldn't build the model flying as depicted.
I remember reading in a different forum a story of a modeller who built the model for a box-photo of Airfix-America (or USA) - there was such branch before. Because the particular model was impossible to built for a real show-picture, he used either Hasegawa-parts or the whole Hasegawa-model for the same a/c.
I believe nowadays making a CGI-picture (they call it a 3D-model but model it is not!) is much easier and cheaper than building a real model for guidance. Always loved the dramatic battle scenes depicting "my" model in a real (or sometimes not so real) situation, rather than a model in scale on same base or just floating in the air on white/black/blue background.
Is this a recent "measurement" you are talking about? Just asking because the "built-model-box-art" I was thinking of is explicitly from the time long before "The Big Ban(g)", not modern stuff.