Ran an experiment over the last two summers with my 2-cycle trimmer. It's always run on TrueFuel.
Fall 2014 I warmed it up, shut it off, drained the tank, and ran it until it stalled. Removed the spark plug, dripped some after-run oil in the cylinder, replaced the spark plug and forgot about it til Spring.
Cranked it up Spring 2015, cranked right up, but smoked for about 20 minutes before clearing up, and ran fine all summer.
Fall 2015, I used it for the last time, did nothing special, and forgot about it until Spring.
Spring 2016, started right up, ran great, and no smoke. Has been running great all this summer.
I really think good fuel is the key, versus doing anything else.