I'm not sure it really matters. My old Colnago has had a lot of parts wear out and get replaced over the years. Generally one or two parts at a time.
It still has the original seatpost, but the seatpost binder bolt broke a while ago. The headset and bottom bracket are both worn, and will be eventually replaced.
Oh, I think it still has the original Universal brake calipers. But, I might eventually get tired of those.
The "New" Colnago, on the other hand, was bought as a bare frame, and assembled as I saw fit. I won't call it the same bike as it was before the previous owner parted it out.