Chewing Gum Lifespan

I've recently started to chew gum on a regular basis. I was chewing Wrigley's Big Red for the past few days. Today I ran out of that and got a pack of Wrigley's Winterfresh. They have them in the snack machines around campus. Anyway, a stick of Winterfresh lasts exactly four hours. How do I know this? Because that's how long I chewed the piece I had before it lost its consistency and turned into a soluble sludge. My lips are really sticky now, since when it lost its consistency as gum, some of it leaked onto my lips and it formed a blue film. Oh well. I don't know how long Big Red lasts since I always stopped chewing it before it gave out. Maybe it lasts indefinitely.