A test can range from 1 to 5 hours, depending on whether you take one or all three sections of Reading/Writing/Math.
The tests are not timed. You are encouraged to give each question as much thought as you wish before selecting your final answer.
It is important to take enough time to carefully complete the test since test results are a key factor in determining the courses in which you can enroll.
If you need additional time, you can exit the test and schedule another time to finish.