How does timing work in Bluebook?

When you’re testing in Bluebook, a timer will be running at the top of the screen so you can pace yourself.  

SAT tests are divided into 2 sections—Reading and Writing, and Math—and each section is divided into two modules. Most AP Exams have two sections as well, and they’re divided into subsections (1A and 1B for example). Each module or subsection is timed separately. You can move back and forth between questions in a module or subsection until time expires. Once you move on from a module or subsection, you cannot go back to it.