I have a content site I wrote about five years ago which (IMHO) is one of two authority sites in a tiny niche. I just got up on my soapbox and wrote 100 pages of everything I knew. Recently I added some tracking software to all the pages and that has been quite the eye opener. Maybe this will be helful to readers who are in the early stages of site development. I now know that less than 20% of the visitors enter via the home page; a week ago I would have guessed 95%. Obviously, I need to re-visit my navigation and see if it works for someone who enters via an interior page. I KNOW I have some deep pages where I don't even have links back to the previous page or the home page I was assuming everyone would be able to use their back button. Only about 40% of the traffic comes from Google. One of the reports shows entry page by search term by search engine. In other words I can see that a Google search on a particular term entered on a particular page. I have found over 100 search terms in the top 30 at Google that I didn't know anyone ever search on. The same search term may deliver visitors to different entry pages depending on which search engine they use. Sometimes the visitor is not going to the best page for what they are looking for. I had been thinking my visitors entered via my home page and then followed my wonderful navigation links to find what they were looking for. I am reminded the search engines index pages, not sites. My little piece of the web resembles a flea market where each page is a table. All the pages that come up for a search term are scattered at random. My navigation has to give visitors directions to my other relevant tables. I certainly have my work cut out for me.
It helps your site to be crawled properly so that your page cache properly. It's better to have top navigation and bottom navigation.
If your site is old and trusted then most of your traffic will come from long tail searches and not via the homepage. Stick some good navigation on the site and you will get a load more traffic.