For a generator you may want to test run every couple of weeks a fuel shut off is good. For the Snow blower and other engines that may not be ran for 6 months or more, it is best to do like my garden tiller, let it run totally out of gas. I have a very small garden and only use the tiller about 2 or 3 times at the start of the season, it will sit for about 11 months. I just let it run empty. Burns up, what, less than a dollars woth of gas. Every year, with fresh gas (I even use the ethanol free and add Satbil) it starts with one or at the most 2 pulls of the rope.