re: OT Managers: How do you hold your direct reports accountable?

Define clear deliverables and due dates, and hold them accountable. If they are meeting their due dates then they are just doing the bare minimum, challenge them to get things done early and ahead of time, find their tipping point and keep them constantly challenged.

And aggressive performance management culture must also be supported by upper management, you will need to just enforce that your expectations are to be outperforming and better than other teams. However, this mindset also involves defining consequences upfront and following through with reprimands or whatever items you have set in place and are agreed by all, including upper management.