Does anyone have expierence with the heritage breed of Buckeye chickens?

I’m a year away from starting my flock, and I’m looking at heritage breeds. And I just kind of doubt that a breed of bird will have the same temperament and behaviors that seem to be common knowledge and repeated facts from source to source, without a breeder actively eliminating “bad” traits from the breeding flock constantly. And I doubt that large hatcheries are actually attempting to do that. For example Buckeyes are supposed to be strong self foragers. But how would that behavior be monitored and breed for without the chickens being in a situation where they are able to forage for themselves and those that do poorly are removed from the gene pool… so anyways anyone have actual experience with Buckeye’s how close do they come to their breeds description in behavior.