Use for sure weakens mag. springs , carry mags will work forever it seems just remove the lint.
It depends on the magazine design. Some carry mags (17-19 rounders) may not last all that long, even if you do remove the lint.
Working (cycling) isn't the only thing that can weaken a coil spring. Hi-cap mag springs, depending on their design and how they're used, can also weaken from being left loaded for long periods.
Note: rotating carry mags doesn't prolong magazine spring life -- it just shifts the work to a different set of magazines. And if the unused mags are stored loaded, it possible that you've done NOTHING to delay wear. (It depends on the mag design and how the springs are used.)
While working a spring can cause wear, the only part of the work cycle that causes significant wear is when the spring is fully compressed the the spring is ALSO near its design limit (also called it's elastic limit). That isn't the case with many magazine designs. But it does happen with many hi-cap mags.
That's why Wolff Springs (in the FAQ section of their site) generally recommends downloading high-cap mags a round or two for long-term storage. (They don't suggest that for the mags IN a carry gun.) The same kind of spring degradation can occur with recoil springs, if a slide is left locked back for extended periods.
When a coil spring is bent too far for too long (at or near it's "design limits", the metal can begin to fracture when held in that position, and continued use at that compression level will cause the damage to slowly cascade, as more and more metal slowly breaks (and the remaining metal must do the same work).
It's bending (compressing) the coil spring's metal that damages the metal, not bending and
releasing it. (The releasing part is good and NOT work.) The farther the metal is bent the more likely it is to be damaged. Metal fatigue is one way of describing it, but that's an oversimplification.
When coil springs in guns fail they will generally degrade (SOFTEN) and quit working properly before they break; they're replaced before they can break. Coil springs in car suspensions, on the other hand, don't keep a car from being driven, so they might eventually continue to be used until they break (from fatigue);l then they're replaced.
On the other hand, if, when a mag is fully loaded, the spring isn't near or at its "design" limit, that spring may outlive the gun in which it's used. 7-round 1911 magazines are like that -- they seems to almost never wear out. And many standard (non high-cap) mag springs in full-size guns also tend to have long service lives.