How do I enable Time Machine local snapshots on an iMac? I have an iMac with a Fusion drive running High Sierra. Time Machine is enabled and backs up to an external disc.

Time Machine takes daily local snapshots so that you can go back to a specific day, even if you don't plug in your backup disc every day.

Unfortunately, this feature is enabled only on laptops, as the aforelinked page says.

How do I tell Time Machine to enable it on my iMac? I plug in my external disc only once a fortnight to backup, but I'd still like to go back to a particular day's snapshot, say if I overwrote a file.
It seems that local snapshots are enabled automatically in High Sierra.



The text in the red box translates to "local snapshots, as long as disk space is available".

I didn't find something from Appe on this, but this blogpost comes to the same conclusion.