@jthr and anyone else on this thread not happy with the status quo:
@popey has done a fantastic video explaining all the commands one can use to control snap refreshes:
https://youtu.be/gVZOBgTDJWc?t=514
You can also read the options for yourself here.
For example, on:
Run sudo snap set system refresh.metered=hold, and head to your Wi-Fi Settings and set the relevant networks to ‘metered’ if they haven’t already been detected as metred. Snaps will no longer update whilst you’re connected to mobile internet, so you won’t get a mobile bill from automatic snap updates.
You can do this. Run sudo snap set system refresh.timer= and use the options in the documentation to set the points in time you want the snap to refresh. If one of these points of time are approaching and you can’t update on that occasion, run sudo snap set system refresh.hold= and use the correct format for the date as detailed in the documentation.
Please also mark yourself affected by my bug report to get all of these options into Software & Updates so that they are accessible graphically and not just via the command line.
If any of these options are inadequate for your purposes, as per the very long discussion about the automatic refresh feature above (please read it all if you can as there has been significant engagement from the developers on this feature and a lot more control over it is now available to users than there was previously), please specify exact (preferably real) use cases which the status quo is not adequate for and please explain exactly what you need to cover that aside from a straight-up off switch, which (former? He doesn’t seem to be an admin anymore or posted recently, who’s in charge now (aside from Shuttleworth, that is)?) snapd head @niemeyer was opposed to unless it can be shown that there’s literally no other way to deal with a real use case without an off-switch.
There’s also an extent to which if you oppose the anti-off-switch approach entirely then obviously this dispute has been going on for a long time and the developers do say that, ultimately, if you don’t like snappy’s approach, you probably should go elsewhere (Flatpak is the main solution that comes to mind).