Reading this brings me some ideas
I'm not a fan of automatic updates, I love to see what I apply, mainly because I want to be able to debug my problems. But I admit sometime when you want to speed up your dnf/yum update, if all rpms have been downloaded before... it is faster.
So in /etc/cron.d/DnfDownloadOnly I have something like that
* 20 * * * root dnf update -y --downloadonly
All my rpms are downloaded for a future installation, for Centos you won't save a lot of time, but for Fedora with about 500MB of updates by week, it is a game changer
Now I'm listening you if you think yum-cron is valuable, or if you have experiences on it.