I don't like medicating unless they have worms. Tape worms have been a little more difficult to eliminate than round worms in my case. I'm not one to hesitate to use chemicals or drugs when it's the most effective and the fastest. But, I don't believe in treating a situation if it doesn't exist. Not to mention you must wait at least 14 days before eating the eggs.
An exception is heartworms in dogs. In this part of the world it is important to have them on a preventative.
As for mites, a proactive approach in the coop and bedding is best. If you handle and check your birds on a regular basis, you will quickly find out whether or not you have mites. You may apply Malaban liquid in the coop, making sure to get in the cracks and crevices. The active ingredient in Malaban is maldison and it can be purchased in powder form and applied on your birds directly.
I have a restricted use pesticide license and I hate to encourage anyone to use a product in a way not listed on the labeling. I have friends who raise large numbers of game chickens. They swab their chickens with the liquid Malaban with no noticeable negative effects. Malaban has been approved for use on cats and dogs and has not been tested on chickens.