The best way to automate garry's mod dedicated server updates?

[APNxRPG24]

I'm trying to think of an easy (or the best) way to automate updates for a garry's mod dedicated server, but the answers just aren't coming to mind.

Bi-weekly or even weekly updates would be sufficient, but the problem is if an update needs to be rolled out right after it just was updated, players would get the error "this server is running a different/older version" and would not be able to connect.
E.g. If I set the updates weekly Sunday at midnight, but a required update comes out Monday, the server will not be updated from Monday-Saturday.

Is there a specific date/time that Facepunch will typically push out garry's mod (required) updates?

Also, is it correct that the server has to be shut down, updated, and then started in that order (i.e. it can't be running while doing the update)? Should the server be restarted when updating source (mounted) content too?

If it helps, I'm planing to run updates using crontab on a Linux DS. I imagine if I can't exactly automate these (unless it's updated/restarted daily), I'll have to pay attention when a required DS update comes out, but please me me know if there's a better way.

Some of these questions might have obvious answers, but I have my doubts, so any advice is appreciated.

[Rubat]

Updates are released quite rarely for GMod, usually once in a few months.

Before each update, we post an announcement at least a week before an update in the Garry's Mod hub.

Most of the time you don't even get the "this server is running a different/older version" message after an update and server can be updated whenever after an update.
For any content, first shut down the server, install new content/updates, start it again.