Negative marking: do you attempt 50-50 guesses in JEE/NEET or leave them?

With +4 / −1, the maths says a genuine 50-50 guess (after eliminating two options) is worth attempting: expected value is +1.5. But in my last few mocks my "50-50s" were right far less than half the time, and they cost me more than they earned.

So either my elimination isn't as good as I think, or I'm calling things 50-50 that are really blind guesses.

What I'm going to try: in the next three mocks, mark every guess, then count how many were right. If it's under 40%, I'll stop guessing on anything I can't narrow to two with actual reasoning.

Does anyone track this properly? What's your personal rule: attempt everything narrowed to two, only attempt in your strongest subject, or never guess at all? Would be interesting to compare with actual hit rates, not just gut feel.