You might think that just one header is enough. Well, depending on the product or service it may be. However, if the service in question is divided and then sub-divided it might be better not just from a layout point of view but also from an aesthetic point of view to do this. Programmatically it makes more sense also. Again, if you have different headers that contain your keywords for that page in question you might find that your page ranks more highly than a competitor's.
There are any number of header tags you can use ranging from h1 to h6. However, keeping it to 3 or maybe even 6 tags maximum would be recommended. This is simply your way of laying out the content much more neatly but behind the scenes search engines will enjoy a layout like this as it indicates the importance of various sections of a page.
Also, ensure each page only has one "H1" header tag.