I've been making rounds (or getting/letting/slacking until Cent or Sal do it) telling allies whenever we even get the idea of signing a treaty with somebody. My little birds tell me this isn't exactly a unique practice, even if there are clear holes throughout CN.
I think the problem is more evident with cancellations. People rarely cut ties on "good terms" anymore, if they ever did. Treaties don't fall until there is not a single hook left to hang it on. So when cancellation comes around, the one or both of the alliances probably (1) dislike the other, possibly intensely and/or (2) calcu