As with AI whining about their new 787s (big shock, I know, but still....), we are pretty used to hearing about the earliest models in a new type of airliner being overweight and a bit problematic. I am aware that pretty much every airliner type made slims down over time, but have there been any examples of a plane that didn't really change a great deal since the first plane rolled of the line? Also, how long are the early models generally expected to last compared to more mature designs? Are there many examples of very early examples of a type hanging around the longest, for instance? Is it always a given that the early planes will be cheaper too?

Grateful for your thoughs.