Final answer:
It's recommended to include a diverse mix of users and devices from throughout the organization when testing updates for Windows 10 and Office 365 ProPlus to ensure all usage scenarios are covered.
Step-by-step explanation:
When testing updates for Windows 10 and Office 365 ProPlus, it is essential to include a mix of users and devices from across your organization. This approach ensures that the updates are tested in a variety of real-world scenarios which reflect the different ways in which the software is used throughout your organization. Including mission-critical devices might be risky as updates can introduce new issues, and it's not advisable to use all users and devices in the IT department as they might not represent the whole spectrum of users. Likewise, selecting only users with specialized line-of-business apps may not provide a comprehensive view of how the updates will function across the entire company.