BethelH that still is a good way because the float bowl level drops to where the jets suck a little air. Then when you turn gas on again next time "new" gas" mixes & freshens what was remaining in the bowl. Give the mower a good shake before you turn the gas on.
In the old days we used to say "you bought Arco (or no-name)? Dont buy that stuff no wonder it gummed up!" And we used to spray carb cleaner into the carb throat while holding the throttle half open, & watch all the crud wash away.
Well that was the good old days - before multi-billion dollar energy companies had ethanol competing for 10% market share (or 15%?). I suppose back then news agencies would publish advertising as news too, but it seemed like you could tell it was "just an advertisement". Same problems, spun different. Internet has sure changed things.