i have 2 big boats, holley 4b on one and a mercarb 2b on the other, have or have had numerous outboards all being 2-cycle, and have the usual: lawn mower, snowblower, weedwacker, and mantis tiller (2-cycle). rebuilt carb yesterday on the mantis that's been a real mf'er .
in all my experience, fwiw, additives in the gas are a complete waste of money. The only surefire solution is pull the carb apart, use carb cleaner and compressed air to clean it out, reassemble and use new gaskets if the old ones can't be salvaged.
the best preventative maintenance, these days with ethanol in the gas, is to make sure you get all the gas out of the carburetor before storage, especially outdoor storage. The ethanol will pull in moisture and water will develop in the carb bowl because it is vented. any other measures you can take are a good idea, such as storing equipment indoors or at least where humidity and temperatures don't change much. Basements are good, outdoor sheds not good.
gas stabilizer doesn't combat the real problem anymore, it's not the gas separating and going bad from storage, it's the water/moisture being pulled in because of the ethanol, and the water ends up forming rust and corrosion which leads to sediment in the carb.