Buying used: how old is too old?

All,

Considering buying some used speakers from a well established company, e.g., Wilson, Focal, B&W, etc.

Aside from obvious technology updates, do speakers have a shelf life? If so is this measured in overall life, or number of hours played?

I’ve read some reviews that some speakers can really improve with age, no doubt longevity is going to be influenced by speaker drivers. Perhaps paper breaks down before other materials—I don’t know.

Old flagships can be bought for a fraction of their original cost and less than new mid-level speakers. No break in needed! But maybe they would be broken down?

I’m sure there have been numerous threads on this topic, but I didn’t find much in my search and am also interested in any recent experience on the topic.

Would be really interested to hear thoughts, opinions, and experience with this.

Thanks!