As a professional woodworker, I’d much rather use my tools than sharpen them, but I know dull or broken bits are unavoidable. I’ve had a toolbox filled with old drill bits, so it was past time to do ...

I've been thinking about buying one of these but I don't know if they are just a gimmick. Also, if they genuinely work well how good do your bits need to be in the first place to be worth sharpening?