There is a big jump in the level of difficulty of subjects for students in class 11 as compared to Class 9/10. Often, students find it challenging to cope up with huge class 11 syllabus, on top of it the entrance exam preparation makes
the job much more daunting. Therefore, examinations such as JEE/NEET/SAT etc need adequate preparation, ideally from 9th grade. The early a student starts, the better will be the performance.