Imagine that your team is in a race, and everyone is tied together. All the runners should arrive at the goal at the same time. Until the slowest/last person reaches the goal, nobody wins.
This is especially true in software projects, but I’ve seen the same pattern in media teams.
Your project is moving as fast as the slowest runner in your team.
That person that trusts no one, works in isolation, that doesn’t realize she is on the critical path.
Sometimes she is the most brilliant, sometimes is the project manager, sometimes is a stakeholder.
The reason why she is holding everyone back is not that she is not getting things done, or the speed as she is moving. It is because she is not working on the critical tasks right now, which will unblock other team members to move faster.
For her, communication is a waste of time, a bottleneck as she would call it. And that’s the exact kind of thinking that makes herself a bottleneck.
If you have someone like this in your team, realize you have two options: 1) find a replacement, or 2) assign her non-critical path tasks.