Applying decomposition strategies in large-scale process mining projects can bring significant benefits, but it also comes with its own set of challenges. Here are the main benefits and challenges:

**Benefits:**

1. **Scalability**: Decomposition allows you to break down a large, complex process into smaller, manageable subprocesses. This makes it easier to analyze and understand each subprocess individually, which is crucial for large-scale projects.

2. **Improved Performance**: By focusing on smaller subprocesses, you can identify and address performance bottlenecks more effectively. This can lead to overall process improvement and increased efficiency.

3. **Better Understanding**: Decomposition helps in understanding the process at a granular level. It allows you to identify patterns, variations, and anomalies that might be missed when looking at the entire process as a whole.

4. **Easier Visualization**: Smaller subprocesses are easier to visualize and communicate. This can facilitate stakeholder engagement and consensus building.

5. **Faster Analysis**: Smaller subprocesses can be analyzed faster, reducing the overall time required for the project.

6. **Reduced Complexity**: By breaking down the process, you reduce the complexity of the analysis, making it more manageable for both humans and automated tools.

**Challenges:**

1. **Identifying the Right Level of Granularity**: Choosing the right level of decomposition is crucial. Too fine-grained, and you might lose sight of the bigger picture; too coarse-grained, and you might miss important details.

2. **Data Management**: Decomposition can lead to a significant increase in the number of data points and subprocesses to manage. This can strain data management resources and systems.

3. **Maintaining Context**: When focusing on smaller subprocesses, it's important to maintain context and understand how these subprocesses relate to and influence each other. This can be challenging.

4. **Complexity of Reassembly**: After analyzing the subprocesses, reassembling the findings to understand the overall process can be complex. It requires a good understanding of the relationships between the subprocesses.

5. **Potential Loss of Information**: Some information might be lost or overlooked during the decomposition process. It's important to ensure that the decomposition strategy captures all relevant information.

6. **Time and Resources**: While decomposition can speed up analysis of individual subprocesses, the overall project time and resources required might increase due to the need to manage and analyze multiple subprocesses.

7. **Stakeholder Management**: Communicating the benefits and complexities of decomposition to stakeholders can be challenging. It's important to ensure that everyone understands the approach and its implications.

In conclusion, while decomposition strategies offer significant benefits for large-scale process mining projects, they also present unique challenges that need to be carefully managed.