In a department I worked in, there were no scheduled 1-to-1, just a weekly slot that was guaranteed to be available if requested. Nobody ever took it. The manager thought it meant that everything was fine, while in reality he had no idea about how people were doing or how they were feeling.

Nobody wants to come to the manager with problems when he's the one with the power and they don't have a trusty relationship with him. And you don't get trust if you don't communicate regularly.