Most people I know (myself included) fill their small engines without waiting 10 or 20 minutes. They want to keep on working without taking a fairly long break.

Do you think commercial mowing companies wait 10 to 20 minutes before refilling gas tanks?

I worked with a guy years ago that smoked all the time while gassing up lawn mowers. I've been told over the years that cigarettes don't burn hot enough to ignite gas, but it is still a really stupid thing to do.