If spare magazines are loaded and set aside for long periods (months), could feeding be comprised due to the spring taking a "set"?

I'm looking for practical experience, not theory.

Depends on the quality of the spring and the design of the magazine.

I had some triple K 1911 magazines go bad in just a few uses.

ISMI springs for S&W M&P magazines are extremely long lived in use and can stay loaded without harm.
In general, it is cycling that wears out high-quality magazine springs eventually, not just letting them sit loaded.
Some govt 1911 magazines fed after decades of loaded storage.

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Science plus Art

Several lively threads about this subject on the forum. The consensus short answer is "No."

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Wisdom comes thru fear . . .

I very respectfully disagree with the consensus. And here's some personal practical experience. About three years ago I bought a pristine Md 4006 with two spare mags. It looked like it had never been fired. I took it to the range and was very disappointed with a failure to feed on the last round of each of the three mags. So, after commenting on this here on the forum, I bought new mag springs. Guess what? Perfect function on all three mags! I'm sure my gun was a night stand gun for twenty or so years. It sat there for all that time fully loaded and ready. Also, the new springs were a lot longer than the ones being replaced. Change the springs!

I've also read here on the forum that some LE departments routinely changed mag springs after a certain amount of time to avoid FTF issues.

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