In short, every student is different. A student with a lower starting score will need more time. Higher scoring students may only need a few sessions. For a student with an average starting score, I generally recommend 20-30 hours of prep over the course of their testing (from junior through senior year). I tailor every program to each individual student, but the majority of my students do a single 1 to 1.5 hour session with me each week. And I'm still able to get better results than anyone else in the world!