The most common shortfalls in manpower assignment in project management include:

1. **Underestimation of Resource Needs**: Failing to accurately assess the number of personnel required for different project phases can lead to delays and increased costs.

2. **Misalignment of Skills**: Assigning team members without considering their skills and expertise can impact project quality. This often results in inefficiencies and the need for additional training.

3. **Inadequate Communication**: Poor communication regarding roles and responsibilities can lead to overlaps or gaps in manpower assignment, causing confusion and frustration among team members.

4. **Neglecting Workload Balancing**: Not distributing tasks evenly can lead to burnout among overworked team members while others may be underutilized.

5. **Failure to Adapt**: Inflexibility in adjusting manpower as project needs change can hinder progress. This also includes not reallocating resources to address unforeseen challenges.

6. **Lack of Monitoring and Evaluation**: Without tracking performance and progress, project managers may miss signs that manpower allocations need revision.

7. **Ignoring Team Dynamics**: Failing to consider the interpersonal relationships and dynamics within the team can affect collaboration and efficiency.

Addressing these issues through careful planning, regular reviews, and open communication can significantly enhance project outcomes.