The Fedora wiki directions for a DNF system upgrade say to update all packages normally with
dnf upgrade --refresh before beginning the version upgrade per se. I can understand that you'd want the latest versions of key packages like the kernel, DNF, and the DNF system update plugin, but do all packages really need to be up to date before beginning the version upgrade? If not, which packages are the bare minimum for the update to work correctly?
As an example (my specific situation), I have a system running Fedora 22, which I want to upgrade to Fedora 24. The system has literally not been used (and therefore not updated) for about 9 months, so almost all packages are out of date. Do I actually need to upgrade all of my packages to the latest Fedora 22 versions (over 3 GiB to download, if not for DRPMs), just to have to download them all again from the Fedora 24 repositories?