I recently had a conversation with client over uniformity of a site.  If you look at two pages (home and about) from your website side by side and they don’t have any elements in common then you are in trouble.  The basic layout and color scheme of your site should be carried out on all of your pages.  It should give the user the feel of navigating though information without leaving the site.

When you give up that uniformity the users mind starts to wonder if they are even on the same site they started at.  More advanced users check the URL to make sure but if your target audience is 35+ then they may not know to do that.  Keeping things uniform, even if it is a simple as having the same header on each page is important in making your user comfortable.  And keeping your user comfortable is key to selling them on your product or service.