Not necessarily, I would expect a new build to have all the same standard of signage basically because the builder would buy in bulk from one supplier thereofre I would expect them all to be of the same standard. The issue tends to come to a head if modifications are carried out which don't require planning permission, signs are replaced because they are old, broken etc. or a fire risk assessment says that more signs are needed or escape routes are changed.
The other issue comes with the architects, designers etc. I have been into a place which had been recently refurbished with exit signs which had pink lettering on a white background. The designer was worried that green signs would conflict with his vision of the interior decor! Yes I did put him right but he was not a happy chappy.