I have never used it. I deep litter and if it did work it would kill all of the good microbes and bugs I want going on in my coop. However I use plain wood ash for dusting my birds. They just take care of it and do maintence all on there own. I use neem oil on the wood parts in my coop to keep lice and mites out. I also use citrus peelings to discourage the pesky buggers. It makes the coop smell nice too. For worm control I give my chickens apple cores and pumpkin seeds and garlic maintence. I breed for resistance and give my birds things they can eat to keep the worm load to a low level. I eat my birds so they have to be healthy.
being 'natural' is all well and good, but if the problem is already present, the birds need help NOW, and some of those more natural remedies may take too long to be effective, so meanwhile the bird is still declining.
I treat ALL new birds coming in the day they get here, because I have no way of knowing what the previous owners did or did not do for maintenance... and 7 days later to catch whatever the first round didn't get. Then I treat everyone twice a year.
some methods work better for some people than others, you just have to pick and choose your methods that work best for you and your situation I think. deep litter method is great in some areas, but on top of our clay-based soil, my 'deep litter' became 'deep muck' whenever it rained more than a couple inches (which happens frequently from may thru july around here).
Gapeworm is one that we have in this area, carried by earthworms. so unless I were to never let my birds on the ground, they're likely to eat the earthworms. and while eating earthworms does not automatically mean they'll get it, I have had a case or 2 in the last few years, so instead of treating AFTER I see a problem, I'll just treat twice a year and prevent any severe problems.
I HAVE tried a number of different methods for keeping chickens/coops clean/healthy, and find for me, raised coops with wire floors, free ranging as much as possible, a good varied diet and using ivermectin keep my birds the healthiest I can.