It should be unnecessary. The keys are rather permanent.
Each firmware contains the buildbot (release / branch ) keys that are needed for installing packages for that release / branch. You do not need the master key 19.07 (and vice versa), as the packages are incompatible in any case.
(There has once been an accidental private key removal, in 2019, and new 17.01 and 18.06 keys were issued, if I remember right. Otherwise there has not been much need for new keys for a firmware.)