That is a general distance for a 200 watt LED. Depending on what brand light you have and how good the light coverage is for that LED light you have, you can probably give or take a few inches. I use a 200 Watt Spider Farmer sf 2000 and thats the distance I use and the distance they recommend. Not every 200 Watt fixture puts out the exact same intensity or spread of light, so find the recommended distance for your fixture and go from there. Like on mine, they recommend 18 inches during flower but I usually end up at about 16 inches. The PPFD is right near 1000 at that distance which is perfect without having to add CO2 and a crazy amount of nutrients.