If you look at the MRIs of brains there are usually large areas that are not doing very much.
The output from this idle state would be less than an active hex-grid pattern; not enough to confuse the L5 layer.
I see this as the background balance of inhibitory and excitatory cells maintaining some low level of homeostasis. It takes some coordinated recognition to organize the hex-grid and suppress the rest of the cell population to make the grid stand out even more.
This is just idle conjectures but I suspect that the total amount of L2/3 activation between when a hex-grid is formed and the idle hum is about the same.
I will conjecture further that the level of column activity is the highest when the L5 bursts to signal novelty, and much less when an active recognition is happening.