The project manager should have prioritized blockers on the critical path. The critical path is the sequence of activities that must be completed on schedule for the entire project to be completed on schedule. It is the longest path of planned activities to the end of the project, and it has the least amount of slack or float. So, if an obstacle or blocker occurs on the critical path, the project schedule will be directly impacted. Therefore, prioritizing these blockers would have been the most effective way to avoid further timeline deviations. References: Project Management Professional (PMP) Reference Materials, PMBOK Guide, Chapter 6: Schedule Management. Professional in Business Analysis Reference Materials, Chapter 4:
Elicitation and Collaboration.