There is plenty of material available online and in form of books for CAT prep. This is the reason that aspirants get overwhelmed and try to practice from varied sources. The approach on the other hand should be to keep it simple. Following are the sources I would suggest:

Maths:

Topic-wise study material of TIME/CL are extremely helpful when you’re at the beginning of the prep. Concepts and shortcuts are specified, and you can get rid of the static friction by solving some basic level questions. As you go on, you can attempt advanced questions which are usually CAT level or above. I also referred to Nishit Sinha which has 3 levels of questions. This book has some errors wrt the answers given, but the detailed solutions usually have the correct answers mentioned.

The approach here is of paramount importance. Aspirants sometime practice from sources which consist of mixed questions from all the topics. This approach at the beginning of the prep can result in missing out some crucial sub-topics. Topic wise practice will make sure that you’re exhaustive in your prep. When you start appearing for mocks, you’ll become aware of your strengths and weaknesses, which will help you to adjust the time you allocate to each topic.

LRDI:

As seen in the last 3 CATs, this section is about understanding new scenarios in a short span of time. The only way to do this is through consistent practice. You can refer to Nishit Sinha and attempt at least 8 sets every alternate day.

From my personal experience, I’ve not encountered even a single familiar set of questions in the actual CAT. But this does not mean that practice won’t help. Being in touch with solving LRDI questions would undoubtedly help you to decipher the new scenarios under pressure on the D-day.

VARC:

Personally I’ve found GMAT material very helpful in improving my RC ability. Although the questions might be a notch higher in difficulty than CAT, you’ll feel pretty confident in attempting CAT level questions once you master GMAT level questions. You can consult GMAC verbal overview for this purpose.

Apart from this this CL/TIME material should be enough for further practice of VA and RC. Again, the secret is to solve 3–4 RC passages every alternate day.

Test Series: I’d strongly suggest IMS test series. It contains CAT level questions, and the number of candidates appearing for mocks are considerably large enough to gauge your performance.

Time Management:

Managing prep with work can be a tedious task for working professionals. I’d suggest you to spend 2.5 hrs on a weekday everyday for the last 4–5 months (depends on your current proficiency level). On the weekends keep aa day for attempting a mock and the next day for analysis of the mock. Chalk out a study plan for the coming week based on your analysis.

Finally, keep it simple, don’t get bogged down, and most importantly don’t get intimidated by your competitors.