JB,
My JD LX266 I never use additive, and I never run the carbs dry. I park it in Oct, and it starts up again every spring.
My JD STX30 with a Kohler 12.5 engine (I'm sure that is not original engine) has some crazy carb issue that floods the motor completely and I MUST shut off the gas and let it run dry.
My Poulan leafblower had not run in maybe 2 or 3 years and it started right up after a few pulls, and the gas in that can is also over 1 year old.
My Stihl Farmboss I was specifically told to run dry by the dealer, but I think it may have gas in it from when LstInThot borrowed it to use on my walnut trees a couple weeks ago (I think I will try to start it and see if I can run it dry).
My Toro walk behind I never do anything to. it starts every spring.
My buddies generator he told me to run the carb dry.
That is my personal experience.
Be well,
David