You Must Try, and then You Must Ask
This is so great.By forcing yourself to try for 15 minutes, you gain a deeper understanding of what you're troubleshooting so that, even if you don't fix it in 15, next time you're in a better position to troubleshoot than you were the last time.And by forcing yourself to ask for help after 15, you not only limit the amount of banging-your-head time, but you also get to see how the other person solves the problem while all the details are still fresh in your mind, so that you'll more likely have a deeper understanding of why what you were doing to fix it wasn't working, and why the ultimate solution actually worked.