Dont underestimate coaching modules, if you complete them thoroughly, then only do extra.
P Bahadur is very good. Even RC Mukherjee is precise with tons of examples.
It also depends on where you are currently with your preparations, if you are finding some chapters difficult or easy, if difficult, then keep it simple and first focus on clearing the basics rather than solving tough problems. However if you think you have time to do more or have firm grip over a concept then try the harder problems.