Look out! I'm bumping my 2-year-old thread today (Sep 12, 2011), because I didn't really get a straight answer, although, AEO's 2 posts were the best.
I have quite a few different frames, and plan to still buy more off Ebay (because used aluminum frames are so freaking cheap), so I'm always changing stuff over between different bikes. The chain I'm looking at has about 9 replacement pins, and still has life in it.
Considering the "a chain is only as strong as it's weakest link" thing makes me think that possibly, in theory, every link could have a replacement pin. No? Maybe that's too simple
Does this quote form Shimano (posted by AEO in post #10) suggest that every 2nd link can have a replacement pins?
"Do not select a previously installed connecting rivet, or a rivet immediately adjacent to a connecting rivet"
Anyway, is there such a thing as too many?