At the risk of sounding snotty, I sometimes wonder about the way people reason. If you don't remove accumulated poop except for twice a month, of course you will have a smelly coop.
I use pine shavings in my coop, changing them once a year for all new. But I use poop boards under the perches to catch the majority of the poop, and I scrape them and clean them every morning. I use tongs to grab any poop that has been deposited on the pine shavings. The coop remains as clean-smelling as when I first put in new shavings.
I completely understand that some people are content with just cleaning poop out every once in awhile, but it shouldn't be a mental stretch that the coop will naturally be smelly most of the time. Even with the deep litter method, the amount of poop generated just in a single night would be enough to make your eyes water if it simply remains until it gets worked into the bedding.
The only way to assure an odorless coop is to remove the poop!