I've squatted. We started our business in one. Commercial property (Grade 1 listed commercial property...), unused for decades, full of leaks, no services, infested with vermin... so we got a DSL line slung over the roof from a friendly neighbour, threw down some sleeping mats and skip-diving desks and chairs, and got started.
We moved out and rented premises and homes as soon as we could, which was after about two years. Nobody noticed we were there (no visibility from any other properties or the street, even though it's bang in the centre of a city), and we left it with no leaks, clean windows, the floor restored, everything repainted and cleaned, and the rats and gulls cleared out.
About six months after we left, they bricked up the one and only entrance, and it's once more sitting there, quietly rotting.
We moved out and rented premises and homes as soon as we could, which was after about two years. Nobody noticed we were there (no visibility from any other properties or the street, even though it's bang in the centre of a city), and we left it with no leaks, clean windows, the floor restored, everything repainted and cleaned, and the rats and gulls cleared out.
About six months after we left, they bricked up the one and only entrance, and it's once more sitting there, quietly rotting.