I fish with someone that I discovered only uses a double overhand knot - I was floored.  

He uses straight braid and claims he has never had his knot fail.  I use a variety of knots and have never heard of anyone using an overhand knot with success.  Does anyone else use this knot?  I have never seen the break strength of this knot listed, nor can I find it.  

 

I told him he should at least learn a palomar knot, and he told me he doesn't need those fancy knots...

If you tie 2 overhead knots in opposite directions, you end up with a square knot, may be what he is doing. Not what I would use, but will hold ok with most braids. If it's working for him, and it holds ok, more power to him.

I use 2 knots without much trouble. Started using braid this year and bend hooks or break line higher up before it breaks at hook. Have arthritis  in the hands and cheater glasses so it is the easy knot to tie. Heck getting old

Back in the 80's when I was a kid I tied that way. My older brother saw me doing it one day and stopped me and showed me a stronger knot. I probably tied the new knot for 10 years before I knew it was called a palomar.

Palomar knot was the first "fancy" knot I ever used.  Probably around 1980-81.  I still use it today.  

Fancy knot?

I once tried using a double overhand knot on dropshot sinker, thinking it might give before breaking line. Nope.

I use to do this when I was kid and from what I can remember I never had an issue with it.  Back then the fancier knots were what the fly fisherman tied.