Consider these tips if you’re prone to procrastination during your test prep: https://insights.collegeconfidential.com/beat-procrastination-sat
Perhaps form a study group with a few fellow students of like-mindedness and book a quiet room in the library and practice together, without chitchatting, taking breaks or glancing at phones. Encourage and hold each accountable.
My son didn’t spend even one minute studying for the SAT or ACT, either the basic or advanced tests. That was just his nature. He spent his “spare time” on his hobbies and his EC’s, which included debate and school newspaper editing. He did very fine on SAT/ACT and advanced tests. That was his “nature.” He had no test anxiety. Just a run-through (not a formal timed test) was all he needed. However, he did have som eearly experience with the SAT offered by the Northwestern University Midwest Talent Search program (which he didn’t attend).
My daughter took a laid-back attitude, but as a result she got good but not great test scores. It didn’t matter much, however, because she was planning to attend art school. I think she rightly focused her extracurricular efforts on preparing her portfolio, which was much more important than her GPA and standardized tests. But when she later decided she needed to take the GMAT for admission to MBA programs at business school she studied intensively, including taking a refresher math course at a local college. And she got excellent scores as well as admission to a top 10 program.
They both succeeded in achieving their admissions goals because they prioritized admissions rather than test scores as such. They ended up at outstanding colleges (UChicago and RISD/UMich).