In PRINCE2, a Work Package is the document where the Project Manager defines the time and cost tolerances for the work assigned to a Team Manager. The Work Package provides detailed information on the products to be delivered, the reporting requirements, and the tolerances within which the Team Manager operates. References: PRINCE2 Foundation official documentation and study materials.

The 'Plans' practice in PRINCE2 is essential for setting up the basis for project control. This includes monitoring, reporting, and responding to project progress in comparison to the planned objectives and outcomes. It ensures that the project stays on track in terms of scope, time, cost, quality, risk, and benefits, and provides a clear mechanism to gauge progress against the initial plan.
= PRINCE2 7 Foundation Training Manual and official PRINCE2 website documentation

Section: Volume B
Explanation/Reference: https://www.prince2.com/blog/the-7-principles-themes-and-processes-of-prince2/

Reference https://www.wrike.com/blog/project-management-basics-prince2-explained/

During the 'Maintain' step of the 'business case management' technique in PRINCE2, the project manager assesses the ongoing viability of the project against the business case, including whether the outcomes are likely to deliver the expected performance improvements post-project. This is a continuous process that ensures the project remains aligned with business needs and expected benefits throughout its lifecycle.
References: PRINCE27 Foundation documentation on business case management.