[Fedora-packaging] When to Obsolete

When should a package be Obsoleted vs letting it be autoremoved by dnf? Example: Say you have a python module with both python2 and python3 subpackages. The only user of the python2 version has switched over to the python3 package. Then you decide to stop building the python2 subpackage. Should the python2 package then be obsoleted, or should it just be left to be garbage collected by 'dnf autoremove'? Scott