CAT, GAT, and Situation Test/Interview, before starting anything, it is extremely important to have an in-depth analysis of it. Especially an exam like NIFT, which is itself a big achievement to crack, requires complete knowledge of every part, every portion, and every section.
If one question is taking you 10–15 minutes, then my friend, you might be doing something wrong. The only solution to this is that you should try to reduce your time as much as possible in mock tests and complete your exam within the given time. At NIFT, your original personality is highly valued. What matters is how far you can take your visualization skills, not just theoretical knowledge. Having conceptual clarity is extremely important.