Everybody has their own opinions. I regularly butcher my chickens and always check the intestines for signs of worms. I've never seen a worm so I have never wormed my chickens. If I saw a worm I'd do differently. Some people treat when they see signs of worms, some treat regularly whether they see signs or not.
I personally believe if you treat whether there is a need or not you can be helping to create a treatment resistant worm. That's why I never treat anything unless I have a clear reason. I don't want to help create a medicine resistant disease or parasite.