Use the Outline button on the WAVE toolbar to see if the web page has a halfway decent, logical heading structure. I was pleased to see that each of the 130 sites used HTML headings, but several sites had heading creep. Screen reader users benefit tremendously from good heading structure, but if a web page has too many headings, this offsets the benefits, and some of these sites have several dozen headings. If everything is a heading, nothing is a heading.
You probably won't have to check your site with all of the available evaluation tools out there, but it is a good idea to do so for the most common web browsers. Just as accessibility software makes it easier for people with disabilities to navigate the Internet, these tools make it easier for developers to ensure accessibility from the start. When you think you've mastered it, go back through the Section 508 compliance checklist to ensure you've met every goal.
This guidance document is not intended to be a final agency action, has no legally binding effect, and may be rescinded or modified in the Department's complete discretion, in accordance with applicable laws. The Department's guidance documents, including this guidance, do not establish legally enforceable responsibilities beyond what is required by the terms of the applicable statutes, regulations, or binding judicial precedent.