He’d come up every day and go ‘say that thing, say that thing’, and I’d go, ‘You’re not Johnny Cash.’
You can’t carry any more than they exhibited any attribute that ever had in their life in every day.
Speaking as a director of actors, I’ve seen overly researching get majorly in the way. You aren’t playing the real person, you’re playing the character in service of the story.
If you play what they do, you start to become them even if you don’t know shit about them.