Supplementals - steer clear
If you have a look at the links to your Adsense site and the first result on Google shows at least a hundred results, but when you go on to the next page of results that reduces to 35 links, you will are likely to see the phrase: "In order to show you the most relevant results, we have omitted some entries very similar to the 35 already displayed.If you like, you can repeat the search with the omitted results included."
So what does this mean? 65 of your pages have been dropped into the supplemental index. If you care about getting to the top of the search engine rankings then you will not want any of your web pages to show up in the supplemental index.