Hello

No , it's not compulsory to study 10 to 12 hours a day to prepare for UPSC examination .

If you start early like one year or two year before appearing your UPSC examination then even focused study of 6 to 7 hours a day is enough but yes it should be on regular basis

Actually more than the  quantity or duration of our hours you put in studies, what matters more is the quality of studying i.e how dedicated ,honest and focused you remain during your study hours.

Follow the below tips to prepare well for your UPSC Examination:-

Go through syllabus well , complete it at least 3 months before Examination so that you can keep the last months for revision as the syllabus of UPSC is quite wide

Top books which you can follow for UPSC examination preparation are listed below subject wise:-

HISTORY

NCERT XI (Ancient & Medieval)
NCERT XII (Modern Indian History)
Facets of Indian Culture Spectrum
From Plassey to Partition - A History of Modern India

Indian Art & Culture

Indian Art & Culture - Nitin Singhania

Polity

NCERT IX-XII
Indian Polity M Laxmikanth

Geography

NCERT VI X (Old Syllabus)
NCERT XI, XII (New Syllabus)
Certificate Physical Geography G C Leong
World Atlas

Economics

NCERT XI
The Indian Economy Sanjiv Verma
Indian Economy by Ramesh Singh
Economic Development & Policies in India Jain & Ohri

Environment

Class XII Biology (last 5 chapters)
Environment by Shankar IAS Academy
Environment & Ecology: Biodiversity, Climate Change and Disaster Management - General Studies for Civil Services (Main) Examination - Paper II and IV - Majid Hussain

International Relations

NCERT XII (Contemporary World Politics)
Current Affairs ( read newspaper as well)

To get the complete list of books go through
https://competition.careers360.com/articles/books-for-upsc-ias

Make a routine or a time table and try to give at least 8 hours to studies , keep short brakes of 20 to 30 minutes after every 2.5 to 3 hours

Read newspaper daily and keep yourself updated with the current affairs

Choose your optional subject wisely , choose the subject you have interest in.

Make short notes after completing each chapter

Revise :- there's no point of preparing for the exam if you couldn't recall anything in the UPSC Examination so you should stress on revision as well.

Solve previous year question papers and mock test papers ;- You should solve these , it will give you idea of types of questions asked and their difficulty level and will help you a lot.

Also work on your communication skills and personality development as it plays an important role in your interview round

For more tips go through

https://competition.careers360.com/articles/how-prepare-for-upsc-ias

Thankyou