It’s wise to promote your internal pages as well as your site’s index page
Why? If you’ve designed your site structure with SEO in mind you’ll probably have a fistful of pages named after your most powerful long tail phrases. For example, one of my sites has pages called:
If you optimise each page for the long term phrase it’s named after, then promote each page in its own right, you’ll drive tightly targeted traffic to your pages.
when someone wants, say, a fluffy green parrot kit, they type fluffy green parrot kit into their search engine
if you promote your fluffy green parrot page well enough, your page will be returned high in the search results
when they click on your link they’re taken direct to your fluffy green parrot kits page, without having to navigate from your home page
provided the price is right a % of them will buy from you
There’s a second bonus
If you’re in a competitive sector and can’t beat the big boys on popular top level key words, promoting specific internal pages could be the best way to beat the competition and get your site in front of buyers.
Last but never least, promoting your site’s internal pages helps your site look ‘natural’ to search engines, who prefer natural growth based on merit to heavy SEO. Whereas having thousands of links to your home page – and none to internal pages – looks far from natural.