If I am to be extremely concise and clear, not at all.
R D Sharma focuses mainly on the board level question which, while might work well during your boards/easy questions, however do not provide you with the depth or the analytic skills needed while solving JEE Mathematics questions.
And btw, Maths is actually the most thought-provoking part of the JEE paper… So, you need tougher books, a higher level and books that make you think…
While you are at it, look up my article on Books for JEE Preparation… the books i used, and found useful… For your convenience, I have also added the links to buy the books on the article itself.
All the best !