Yeah, it still applies. Not as much as with COB's, because the strips already have the LED's spread out - but only in one direction.
IIRC, the LED's in SolStrips have a "cone" of 120 deg - BUT - the light intensity is not uniform across the entire width of the cone. The lights are brightest directly under the LED's and it drops off in a non-linear way as you move out from the center.
Here is the graph.
The 120 degree angle is chosen because thats the point at which the light intensity has dropped to 50%. Actually, its less than 50% - more like 45%.
So, at the edges of that cone the light is less than 1/2 of what it is in the center, directly under the LED.
That means that you get more even coverage the further away the light source is from the canopy. The problem with moving the light further away is that the light intensity falls off as the square of the distance.
Thats why its good to have extra power available - you can move the lights further away to get more uniform coverage and still have enough light intensity on average.