To me, it's all about whatever the op was trying to get to.
"Show us your Heller builds" or something like that, however old, is not a Z thread. As long as a response makes sense, it only adds to the subject.
"Need help finding a Heller Spitfire canopy", is not worth responding to after say a year, and is a Z thread. If the poor guy hasn't found one by then, it's too late.