> For Automake, I don’t think it makes sense, though.  Or did you have
> anything special in mind?

Dependencies.  For instance, you're updating Foo that requires Bar.
(There is Bar-41 in the repo, but this version of Foo requires 42.
Also, Bar-42 has some backward incompatible changes.)  If you update Bar
to 42, it will break other packages.  I suggest to keep three versions:
the latest version, second-to-last, and third-to-last.

Nikita