The syllabus for JEE is vast with not one single handbook for help. While you have been competing with a batch of 200 students at the school, JEE is about lakhs of students aiming for a handful of seats. Experts give you the insight to prepare for the upcoming JEE. So you should be friendlier with the books and follow that.
Article source: https://docs.google.com/document/d/1sG8qp4P25fY5hXGjmBaHV6DSDbcYI0tvSRxTyrTKQmM/edit