It is something we do dozens of times a day and even more if we parent young children.  Hand washing is often overlooked as one of the most important ways to prevent the spread of viruses such as the flu.  When I had a classroom of little ones I kept waterless sanitizer next to the tissue box (and though this type of sanitizer is not good if over-used) and it helped keep my students and me healthy.  We washed hands as a class before lunch and I wiped down most surfaces that were touched by students including door knobs and light switches at the end of each day.  

As a teacher you quickly learn the importance of putting germs in their place.  In my daughter's preschool the children sign in and wash their hands at the beginning of every day.  The class has had very little illness all year.

We can't completely protect ourselves and a little exposure to germs here and there is actually good for us, but at very least children should know how to wash their hands properly.

I'll admit, I don't always do the whole drill myself at home, but sometimes 20 seconds is just too long when you have a toddler about to draw on the wall.