Are those times for cells that have been stored in unused condition,
or for cells that are in a device which is in occasional use?

Unused, of course. Using the cell, even "occasionally", drains it.


I believe that the former (shelf life when fully charged) is often a
good deal better than the latter (lifetime once partially discharged).
I've read that even a modest partial discharge of an alkaline cell
starts an electrochemical reaction that can lead to corrosion of the
case after a year or so.

I've never seen this. Sounds like another myth started by someone who
doesn't understand.

The electrochemical reactions in batteries continue at all time, whether
they are "new" or used.