Actually a good question. Sometimes, the level of vibration and sloshing around a prarticular bike does, along with boiling the gas
is enough to keep it worked out. If you have a high water content (technical alert) say, over 15PPM water, sometimes your performance can suffer enough for you to notice. If you have a decent flow rate, a hot carb
,an a little vibration (like us!) it does kind of work it's way through, although a big slug of water from the tank is a party foul you won't be able to get past with a little rough running. I drain my float bowlevery time I do a 8000 mile service check, but that's me.