I've been tying shorts for more than 35 years. I can do it with my eyes closed. I can do it while running, or while swimming. I don't need to look down, finagle an end into an ampersand and whatnot. I don't have to worry about grabbing the right loop+end combo to increase or decrease tightness. I just undo the knot, and redo it according to preference.

I'd argue I'm just about as fast adjusting my shorts than this guy in the video.