Changing inner tubes

[abgd]

I recently found an inner tube from 1974 in a permit aircraft that I bought, which was flying up until 2012:



I have to admit the inner tube seems to be in reasonable condition. But do you typically change them more frequently than this? If so, then how do you decide when to change them?

(I do have an inspector whom I trust, and the inner tube has already been renewed. I'm just curious to see whether there's any spectrum of opinion on the matter).