I don't think it necessarily makes you a bad mathematician either. We all sometimes focus on a problem and start thinking inside the box whereas it has a simple out-of-the-box solution that we're missing because of our focus. Just like a novice programmer can sometimes easily spot an expert programmer's bug in a mere of minutes.
Ones that get you stuck are the best ones. That's the ones with potential to teach you something you didn't know and improve your skills. Find a way to fall in love with training. Don't fixate on holding the trophy.
