Help regarding improvement exam

Shall I give CBSE improvement exam or not?

Hey! I am a student of Class 12,Commerce, CBSE. I have queries regarding the CBSE improvement exam. So, I couldn't score 90% by 3 percent, so I wanted to give the Business Studies improvement exam so that at least my overall percentage will be above 90%, because I am confident about it that in Business Studies I can score well. It used to be my strongest subject, but CBSE OSM, you all know. Anyway, so my plan is that I will give Business Studies improvement exam this year and then the next year as private candidate I'll give Accountancy improvement exam because in that also I have less marks than expected (CBSE allows such exams). So yeah, that's my plan.

Also, I wanted to ask if I give all these improvement exams and I score higher than before, so in any field, I go for job or education will they consider my original marks or the improvement exam marks and then calculate my final percentage.

Please help me regarding my queries.