The UPSC civil services exam is considered one of the toughest exams in the country. And, because of this, a lot of people recommend studying for about 15 hours per day during the IAS exam preparation time.
The UPSC doesn’t expect you to know everything. There is a syllabus that you’re supposed to stick to. There are standard books available for reference. What is expected of you is to have a general understanding of the given syllabus that is enough to pen down your thoughts diagnostically and conceptually. I would recommend don't study for 15 hours a day. But yes consistency is important.
The UPSC civil services exam is considered one of the toughest exams in the country. And, because of this, a lot of people recommend studying for about 15 hours per day during the IAS exam preparation time.