I agree. When I started reloading, I shot a lot of Bullseye, W231 and WSF so I bought 8 lb jugs of them. Out of curiosity, I left some powder in the original plastic containers. Over the past 18 years, these factory containers were stored in the garage where temperature ranged from 40F to 105F+.
From time to time, I smell the powder and load some to test and they still have a clean solvent smell and work well without any signs of powder breakdown.
YMMV depending on powder and storage conditions.