Hello,

I would like to tell you that it does not matter as it depends upon your determination and your hard work.

People refer from other books as they are reference books as they are specialized in that particular topic.

I would like to mention some good books for MECH GATE below:

• Machine design - V.B. Bhandari
• Engineering Mechanics by Bhavikatti
• Fluid Mechanics by R K Bansal
• Heat and Mass Transfer by J P Hollman and R C Sachdeva
• Industrial Engineering by O P Khanna, Buffa, and Sarin
• Production Technology: Manufacturing Processes, Technology and Automation by R.K. Jain
• Strength of Materials - Gere & Timoshenko
• Strength of Materials by Gere and Timoshenko, B C Unamia, Sadhu Singh, Ramamrutham
• Engineering Thermodynamics by P.K. Nag
• Theory of machines by Ratan

As you can see, these books are very good for particular topics and thus you can refer.

I wud suggest you visit the careers360's ink given below which has a detailed explanation of the books for topics.

The link for the same is:https://engineering.careers360.com/articles/what-are-best-books-for-gate-me

Hope this helps and all the very best!