Usually its a good idea to add a fuel stabilizer and keep the tank full. This keeps the amount of varnishes etc from building up. Also its best to either give a bike a long ride or not run it at all as just starting it and running at idle creates more chances for condensation of moisture in the oil system thereby creating more problems.
It's best to keep the tank filled to the top so condensation doesn't form.
With the evaporative emission canisters we have on our fuel systems on today's vehicles,it's almost impossible for any of the good stuff to evaporate.
In my experience,gasoline will stink of raw turpentine when it has gone stale.Once stale gasoline turns a golden brown,it's time to drain as much as possible,then run a couple of gallons mixed with concentrated fuel injector cleaner to chase the old stuff out.Then just fill and run it as you normally would.
I use the cheap stuff from the store everyone hates because it costs $1.23 a can compared to sponsoring a race car team @ $9 a can for the same exact chemical.
Stabil works great in my equipment like generators that sit for many months at a shot.
I have only seen gasoline lose it's volatility if it sits exposed to the atmosphere.This is why race fuel storage tanks use a bladder for storage.Never buy race fuel from a large tank that doesn't have a bladder cover over the fuel.
Racing alcohol and the vehicles system needs special attention after every race is over.
Plus you'll know it is bad by the way it idles and runs, etc... Usually during the 3 months of winter, it should be okay. I always use Super Unleaded and never had have a problem. I even let gas sit in a Honda 650 Nighthawk for 2 years and it still started but ran like the carbs needed cleaning-LOL!! Added some more new gas and off she went!