I'm not so sure. At my last company, we sold to four reasonably separate industries with a small amount of overlap. The four lines of products had nothing in common to look at - different shapes and styles, different colours. The marketing department liked the different colours because it made sorting the propaganda
cough sorry, I mean 'info packs' easier. But the effect was that there was no commonality in the field - a user from one industry crossing into another would not recognise our equipment.
For the marketing power of unified forms and colour schemes, see Apple. Colour schemes all by themselves probably aren't enough, but they are a fundamental part of 'form'.
