It's not an approximation. For a singular light source the inverse square law is always the same. Twice the distance = a quarter of light intensity.
Multiple light sources do counteract the inverse square law.
Example. 3 seperate lights in a row. Each a single point for a light source (not a board ). Spaced 2 ft apart.
The further below the light you get the more of that lights intensity is lost but assuming a dispersion of 120° at 3 ft below the light source the 2 lights furthest from one another have overlapped. Granted the light has to travel 5 ft to the point of intersection and light intensity is reduced it still counteracts light lost from the inverse square law. And this doesn't even account for the middle light which would reduce the effects even further than the far light
Multiple light sources do counteract the inverse square law.
Example. 3 seperate lights in a row. Each a single point for a light source (not a board ). Spaced 2 ft apart.
The further below the light you get the more of that lights intensity is lost but assuming a dispersion of 120° at 3 ft below the light source the 2 lights furthest from one another have overlapped. Granted the light has to travel 5 ft to the point of intersection and light intensity is reduced it still counteracts light lost from the inverse square law. And this doesn't even account for the middle light which would reduce the effects even further than the far light