/k/ here, I want to know about fucking springs. Everyone on /k/ is too stupid to make up their mind and I'm too stupid to know the answer.

What causes springs to wear out? Constantly compressing and decompressing them, or keeping it compressed for long periods of time. If they both wear the spring out, which is worse? While I'm talking about steel springs in particular, what other factors come into play than just the one's listed above, in wearing out a spring, if any? Also, specifically talking about springs relating to firearms, magazines, etc.

Help I'm retarded and I can't get up.