Here's how I do it.
I have a local mirror on my test machine, updated by a daily cron job thanks to mirror-slackware-current.sh
slackpkg point to mirror1, where I run upgradepkg manually to see how it goes.
If everything's fine, I publish the updates to my LAN http mirror.
Other machines' slackpkg points to http://my.lan/mirror
, and slackpg is run from cron job.
Kind of a "poor man deployment tool" without the hassle of advanced solutions like puppet.
I don't need a puppet-like tool for my family machines, but it might be worth the trouble for a larger network like yours.