Does that help prevent the gas from gumming up the carb and fuel lines?
I always thought that you were better off emptying out the fuel system to keep the deposits/varnishing/gumming down...
I didn't drain it one year, and the next season, it was hard to start, and ran rough when I did get it started, but then started to run better after running for a while. Like the deposit/varnish started to wash off/clean out as I ran more gas through it...