I try to keep enough cash on hand for 2 months of living, and I normally keep enough food for a month or so just by buying extra of what we normally consume. I say normally because we've just moved so it'll take some time before we're stocked up.
That is probably more than most people do. I would aim for that too, it is prudent in case of any emergency.
The biggest threat in my view is the panic that happens at even the threat of a problem. It causes problems that could be avoided. Like the toilet rolls rush during covid.

