Yes, you must read the entire spec. Every page. And then memorize it.
Reading the spec is *not* required.
The spec (especially *these* specs for servlets and JSP) are not really *intended* for web component developers; they are designed to be used by Container vendors. While the EJB spec, I think, is a much more usable document for developers, the Servlets and JSP specs are not quite as appropriate (and again, it was never the intention of those documents).
The reason to turn to the spec is if you have a question about something, then you can try to look up the final word in the spec.
If you have the HF book, we wrote it specifically so that you would not have to refer to the spec. We do not cover *every* possible thing that IS covered in the spec, but the exam takes a more real-world approach that as a developer, there are things you are far more likely to encounter as opposed to others, and those are the things in the exam and book.