Hello,

 To Be Frank, NCERT is indispensable for BIOLOGY as about 73–78 questions are directly linked to NCERT and without studying NCERT you may not able to answer some questions like a question was in last to last year that what is responsible for extinction of an organism. Actually the answer is Habitat loss and fragmentation but some books and coaching answer keys give another answer but here the answer will be preferred which is written in NCERT'S textbook. So if you will religiously follow NCERT for BIOLOGY then I assure you that you can correctly answer to more than 80+ questions in NEET. But you have to solve last 10 years questions of Biology as most of the questions are linked from the questions of previous years.

For Chemistry you have to read NCERT for theoretical questions of Inorganic Chemistry i.e. d & f block elements, Hybridization, Alkali Metals, Coordination Compounds (most important) etc. And last 3 chapetrs of 12 NCERT'S Chemistry i.e Chemistry in Everyday Life, Environment related questions and Biomolecules.

For Physics rely on your coaching notes and one Reference book like HC Verma and solve at least 10 Calculative questions from different chapters.
And most important always hope for the best

Hope this helps. .