Three days is way too little, it's a normal amount of supplies anyone should keep in their home. "Stockpiling" would be over six month's supply in my view, anything less is normal household management.
Think back to the early days of Covid, how quickly the supply chains fell apart and how long it took to get a reliable supply of things like pasta and toilet roll back in the shops. And that was during peacetime where supermarkets were working overtime to get stuff delivered and on the shelves.
The most important thing is a supply of enough water. In a SHTF scenario a lot of people will die of thirst long before they die of hunger. It's difficult for someone like me who lives in a flat but I've always got enough water to keep me going for a few weeks. Food you can cut down on and make whatever you've got last longer if you ration it. Few of us have a reliable private water supply though (and those that do need to plan for if the supply gets tainted by chemical warfare).