For traditionally-managed projects, two assumptions guarantee project completion delays:
1️⃣ Project task times is predictable, and
2️⃣ Traditional project management system is effective.
We ask resources to provide an estimate of the time required to complete a particular task.
Once resources have reported their estimated (and safe) times, management requires lower estimates.
If everyone accepts these estimates, the estimate becomes a commitment. Resource is then evaluated on their commitment.