Depends what an individual's idea of self sufficiency is? 500 years ago, our ancestors were all self sufficient since there was no power grid, municipal water supply, mains drainage etc. Shops and market stalls existed and many people were employed on the land. So they were in that sense dependent on their employer for wages, but equally he relied on them to successfully run his farm, so it was an interdependency. The only way the average peasant survived was by growing what he could, and if lucky, keeping a few hens or ducks, definitely snaring whatever small mammals he could. The only heat and light came from fire and the law allowed him to gather fallen branches on the common heathland and woodland. The only water available was from a stream, river or communal well.
When I see programmes like 'Alaska, the last frontier', I am shocked at how sophisticated a life these people strive after. Although they aim to be self sufficient, they have thousands invested in complex machinery and equipment. In order to acquire this and to keep it ticking over they must work harder and harder. The amount of food they deem necessary to get through a winter, I would say would keep a village going. The greenhouses and polytunnels would not disgrace a commercial vegetable growing enterprise.
There are simpler ways of self sufficiency. It is perfectly possible to grow all you need for a year without spending every waking moment at it. If you concentrate on seasonal vegetables you don't need to can vast quantities, you can use them as you need them mostly from the ground. A windmill to generate electricity would give you power to run a freezer and fridge. Cooking and heating can be by woodstove. A few chickens and ducks, and a dairy cow for milk, cheese and butter. Even allowing for repairs to structures etc, I think 2 people could quite easily maintain this lifestyle working for about 6 hours a day each.
