Pai from Portugal writes and asks: „How can I make sure that Google reaches and indexes pages that are on a lower (deeper) level of a website?”
Well, it's unclear whether you're asking about how many levels deep it is in terms of directories or how far it is from the root-page?
One way that you can make sure that Google reaches those pages, is link from your root-page, your main-page, directly to the deep pages you want to be crawled. So we tend not to think about how many directories deep a page is, but we do look at how much PageRank a page has.
So if a lot of people link to your root-page, then you can link to sub-pages and then those sub-pages can link to other sub-pages and at some point, then we'll stop crawling.
So one thing you can do, is you can try to make sure that as many pages as possible are within just a few clicks from your root-page. A good way to do it is prioritize which pages you think are the most important. Either they convert the way that you want or they have a really good ROI.
So, don't treat all of your pages the same. If you've got a few that are just like money makers, try to surface those and get them kind of linked to from your root-page so that you make the most of that.