It's important to remember that poison ivy berries are a very important migratory bird food. I leave it in areas where people don't go. It means weeding bird planted seedlings out of garden areas but worth it for the value it adds to the habitat.
I would never attempt to remove it all from a natural area, but I did occasionally remove it from the edges of our most-traveled hiking trails at a camp I worked at. There were still plenty of plants in less-traveled areas to feed the birds.