Google Supplemental Results Index is NOT a place you want to be! The way you end up in there is if your pages are so badly described or categorised, Google could scarcely decide if there was a difference between them. Bottom line is, if you don’t take the time and effort to make your pages unique, with page URLs, Titles and Descriptions that accurately describe the contents of the page, why on earth should Google even bother indexing them at all? That they do so is a credit to them, even though they no option but to park them in the “Other Crap We Found” bin… If a check shows that not all your pages are indexed, it makes sense to commission a website audit report to determine cause.
Duplicate Content Allergy
Everyone who bothers to read the Search Engine Guidelines would know that Search Engines loathe duplicate content with a passion bordering on paranoia… Three of the key “uniqueness” indicators on a web page are its URL, Title and Description. If all pages have unfriendly URLs containing “&, = or ?” and not a keyword in sight, that is a very bad start. Compound that with generic Titles and Description meta-tags, and you’ve gone a long way towards obfuscating the reason that the page exists.
Do a Google search for “site:www.mysite.com” (replace “mysite” with YOUR site’s domain name) for obvious reasons… This will show you what they have found and indexed on your site… You will see the individual page URLs, the Titles and Descriptions… All different, are they? If not, you have a problem! Not only must they be different, they must be accurate!
Search Engine Results Page
Bear in mind that in the event that one of those pages actually finds itself thrust into prominence in a Search Engine Results Page, it needs to capture the interest and attention of the viewer… and if they click through to your site, its important that they find what they were looking for! If not, they left already! That is twice as bad as you might think, because Google actually takes note of how long they stayed… and factors this into your site’s relevancy for whatever term your page was found for. If people are going to you and staying for a while, the “stickiness” of your site can increase your rankings for that search term! Conversely… if they are leaving immediately, your page will decrease in value as a consequence.
Unique Content is Good
As a general rule, your goal should be to make sure that every page on your site is unique / different. It should focus on 1 – 3 specific keyword phrases that will draw people in via search engine results pages, and it should provide information, entertainment or something of value related to that term or terms. If it does not do that, there seems little point having the page on the site in the first place!
Optimisation of a site is all about accurately describing the contents so that its obvious to both automated Search Engine spiders AND human viewers. That brings the “qualified traffic” flow of visitors who know what they want, and that your site probably has it!