Deep Litter *may* never have to be cleaned out at all -- if you get that perfect balance.
Most people end up having to shovel it out after a long while when it's piled up high enough to start spilling out the doorframes. :)
Some people do manage to achieve the perfect balance of poop, litter, and moisture to create compost conditions that break everything down at the perfect rate.
I wouldn't actually want to myself because I want to be able to harvest compost for my garden. :)
You can keep it as just dirt for a bit, but the poop will start to build up and then you'll want some bedding.
My primary bedding for the coop is coarse-flake pine shavings but I also use a bit of pine straw, dried lawn clippings, and occasionally straw.
My primary litter for the run is pine...