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.