I’m currently reading an accessibility book. I’m not quite ready to post a review of it yet, because it’s very lengthy, but I got so excited about a new piece of information in a chapter of the book by Jim Thatcher that I just had to say something about it.
A modern screen reader can navigate using heading elements (h1 to h6). Using the H key, a person with a screen reader can jump from heading to heading to get a sense of how the page is organized and find the content they want to hear. (Opera uses the S key.) This means a well structured page with textual heading elements (or their equivalent) identifying each major content area of the page can be quickly understood just from the headings. Skip navigation links are not needed in a page with informative heading text. In particular, there should be a good heading indicating the main content.
When using skip navigation, the most useful link is to the main content.