Hello!

I'll get straight to the point!

Engineering:

KCET: KCET ranking depends upon both, your board as well as CET marks! Hence, write your board exams well! My personal experience goes like - I didn't do my CET well, but because of my board percentage which was quite high, I was able to bag good ranking!

JEE and NATA: JEE and NATA ranking does not depend upon your board marks. So you bag qualifying marks in your boards and work hard for your JEE exam! That'll do it!

Medicals:

NEET: Again! Just like JEE, NEET ranking does not depend on your board marks! But it is to remember that NEET questions is based on your board portions, so preparing for boards will help you prepare for NEET as well!

Bachelor's in Science, Arts and Commerce:

Here my dear friend, yes, board marks play a very important role! The higher the percentage, better will be the colleges you can get! In order to get admitted into your dream college, you have to get good marks in your board exams.

Note:

Because of the increasing competition where every student is able to bag a good CGPA or SGPA, companies showing up in your campus will not only consider your semester marks but will check your board percentage as well!

Conclusion:

Let us agree that in this poor education system where theoretical learning is given more importance than practical learning, marks play a very important role! Thus, you should go ahead and work hard because no matter what, higher your marks, higher will be your chances in this fast moving life!

The more you get the more you get benefited there is not a specific number for good career even there are cases that failed class 12th examination also doing good and their career and there is other side also but if you consider the chances then better marks in class 12 will give you  chances of good career their phone to be eligible for most of the exams and shortlisting 75% is the minimum but there is not any e specific limit the higher you reach the better you will become.