Is there a common way of auto-updates with cron?

I run Ubuntu and Fedora on a day to day basis and usually run the package manager to check for updates nearly once a day. When I get a kernel update I usually reboot, so that I'm running on the new kernel and I can see if there are any glitches (It's almost always fine). If I add apt-get update && apt-get -y upgrade or dnf check-update && dnf upgrade to my root crontab is there anything procedurally wrong? What if I set up crontab to do this at 4 a.m. and it installs a new kernel, then I don't reboot and it auto-installs a second new kernel. What if I don't reboot my Ubuntu box for a month and there have been 3 kernel updates and a couple of other patches to the same piece of software during this time? Is it OK to enable automatic updating this way? I know that there's an 'unattended upgrades' utility for Ubuntu, but I'd rather learn what other system admins do and have a more 'hands on' approach to administering my PC's.