OBS style VOR is still kind of important for a heading failure on a glass cockpit tho
Then that's either the failure of my CFI, or whoever wrote the IR program at the school I attended. As that was never taught to me. What was taught was if all fails use the magnetic compass. And how to fly with it with the lag and the errors/delays.
But it is what it is. My explanation will be that I after that failure, I learned to always be prepared.