Now, considering your self-preparation time is almost 3 months and you have completed your tuition, you would probably be allotted 10 days for each subject.
But what if, while making the preparation chart, you make a minor change and allot just 1-2 days for test series in each subject, i.e., if I am sparing 10 days for advance accounts, I will try and complete my revision within 8 days, and the rest 2 days, I will attempt test series.

Absolutely yes! If done effectively, 8 days is a good time for revision.

There are many test series available in the market, but it's always better to choose one that gives you evaluation based on the ICAI / ICMAI format.
 

Why does this matter?

Even ICAI / ICMAI provides mock papers for practice. But if no one checks your answers or tells you where you went wrong or how you could have done better, then just solving the paper doesn't help much.

That’s why it’s important to pick a test series that includes proper paper evaluation. It helps you improve and prepare better for the real exam.

During your exam preparation, once you are done with a primary revision of the subject, you can attempt your first test series. Further, once done with the final revision just a few days before the exams, you can attempt a detailed full syllabus test series.

How would they help?
The first test series would help you in letting you know the areas you need to concentrate on more while preparing the second time, and the final revision would help you know the topics to be revised just before the exam day.