When you do not have time to complete the SAT in one sitting, it is still effective practice to break the test up into two sittings or even individual sections. Whenever you complete any part of a practice SAT, make sure to do so under strict, timed conditions. Managing the time constraints and finding the right pacing that works for you is a huge part of getting prepared for the SAT. Do not give yourself a few extra minutes to finish as even these few minutes will permit you to complete a few more questions and can greatly inflate your score. The practice tests are great for finding your weaknesses, so be honest with yourself, keep strict time, and then work to improve your score.
3) Never do practice SATs off the computer.
Print out the practice SATs! I cannot stress this enough. We have many students who just pull up the tests on their computers or tablets and work from there. Without the paper copy, students will lose time scrolling back and forth and usually cannot complete the test as quickly. In addition, it does not allow students to build good test-taking strategies, such as annotating in the Reading Test, crossing out incorrect answers in the Writing & Language Test, and labeling figures in the Math Test. You'll be given a big paper SAT booklet on test day, so print out the practice tests and treat them like the real thing.
4) Review your practice SATs.
Taking practice tests is only useful if you learn from your mistakes on the practice tests! After taking a practice SAT, you should take time to review every question that you missed AND every question and you got right but were not 100% confident on. If you don't know why you missed a question or exactly why you got it correct, you are not going to improve on subsequent practice SATs. Once you find your areas of weakness, put in some study time focused on your areas of weakness before taking another practice SAT. If you want to see your scores improve, you need to spend 1-3 hours reviewing your practice SAT.