Take an exam unprepared vs Skipping it Which one is better? Taking an Exam with no preparation done beforehand or Skipping it altogether?

I have done the former (i.e take tests unprepared) a lot many times than the latter - so much that I have gotten sort of used to to it. I have observed that if I have insufficient time for preparing for an exam, I don't study as hard for it as I would have before adopting this practice.

My mentors are of the view that one shouldn't ever skip a test. That I'll learn more than just something at the cost of sitting through those hours of the exam.

Is this worth my current subconscious habit?Is it good to continue this if I find that the frequency of me taking half-prepared exams is increasing ?

PPS: I am talking about a Multiple Choice based exam with Negative marking present in it.These are sort of Practice tests for the main exam.

PS: This is NOT a debate or discussion. I Genuinely want to know which is better for improvement in academics.
Students usually decide this based on the consequences of each option. At some universities, you can retake failed exams but you cannot retake passed exams to improve your grade. In this case, it might be worth skipping the exam instead of taking it and "risking" obtaining a low passing grade that you cannot get rid of.

It might also be that you the rules give you only a couple of chances to pass this exam, so you do not want to miss this chance. Or that you do not care about the grade as long as you pass, so you might as well have a try. Or that past exams are not made available to students, so it might be worth for you to go and learn how exams in this subject look like.

If none of the above applies (i.e., if you know you will fail anyway and are only asking whether the time spent at the exam will be worth it in terms of how much you learn), I would say that those hours would be much better spent learning the subject or doing practice exercises on your own. Surely you will learn more by doing exercises in a comfortable environment (at home or at the library) than by doing the same exercises in exam conditions.