well if you have done any hand washing research it takes longer then 20 seconds. im a nurse so i kinda have experience and knowledge of how handwashing works, they say the friction works with out soap even but my point is covering your entire hand with good enough force in 20 seconds is a little fast as it always takes me longer and i also like to cut my nails to nothing and scrub cuticles.
Question for you. Ever heard it's a good idea to hold you hands still for 5 or 6 seconds after vigorous rubbing during washing but before the rinsing begins? I can't find anything on the net or any person that I've met that's heard of this. I read it in the pre internet days in a magazine in the late 70's.
The reasoning is it allows the soap film a better chance to surround and cling to the dirt particles. So the final rinsing will more easily wash the dirt and germs off.
Talked to doctors during my checkups and they never heard of it but they're all younger than me. Btw been washing my hands like you mentioned for years taking almost a minute including the lengthy rinsing. I'm not in the medical field, just drafting, graphic arts and some computer programming.
The closest any internet article came to this (edit: that I know of) was a casual phrase in a state's guidelines for washing hands, maybe it was Michigan or some state. It said after the dirt particles have had the time to be isolated by the soap film then rinsing can begin or more rubbing and then rinsing.
My feeling is they danced around the idea of holding your hands still for even 5 seconds. Can you imagine how much more water would be used by people all over the world if everyone did that for 5 or 6 seconds at every hand washing? And people would double it to 10 seconds or more to be thorough and water bills would go crazy.
edit: Anyway I've heard vigorous rubbing is fine as stated in official medical guidelines all over the US so maybe no need to hold the hands still. It's just a theory.