Most of us who use deep litter never clean it out. If you are using deep litter and it's "stinky" you either have a higher poop load than the litter can handle (too many chickens in too little space), a moisture/drainage issue, or the litter isn't properly managed (not enough browns to offset poop).
Coop cleanouts vary wildly in frequency based on many factors: litter choice, poop load vs amount of litter, your climate, etc. I clean out my coop twice a year but could probably get by with just once a year. That works for me because I pick up poop under the roost daily, I have a lot of ventilation and air volume in the coop (to keep moisture out), and my deep bedding stays dry year round.
No. Aart's post has a link that explains the difference:
https://www.backyardchickens.com/th...-method-with-this-coop.1075545/#post-16440037 it has nothing to do with where the material is, it's what's in it and how it's managed. You can do deep litter in a coop but most coops are not set up for it.
Permethrin has nothing to do with microbes. It's for killing mites and lice. If you do not have an infestation, there is no reason to use it - it does NOT work as a pre-treatment.
What is the DE for? Grain mites are the only thing that folks on here seem to agree it works on.