In the Scrum framework, when an inspector determines that one or more aspects of a process deviate outside acceptable limits, an adjustment must be made as soon as possible. This is a core principle of Scrum's empirical process control.

Product Backlog refinement is an ongoing collaborative process where the Product Owner and the Developers review and adjust the details, estimates, and priorities of Product Backlog items.

The Scrum Team decides when and how to refine the backlog, usually spending no more than 10% of the Developers’ capacity. While the Product Owner may update items anytime, they work independently from the Developers — though they can seek support from other members as needed.

The Scrum Master serves as a facilitator and coach, not a decision-maker or manager in Sprint Planning. During the event, Scrum Master ensures the timebox is respected, helps participants understand the purpose, supports effective collaboration, removes impediments to productive planning, and ensures the event achieves its intended outcome.

Sprint Planning is a collaborative event where:

• The Scrum Master facilitates, makes certain participants understand the sprint goal and backlog items, helps the team select work for the sprint collaboratively, protects deliveries against over-commitment, and guides the team to focus in creating a realistic plan to achieve the sprint goal by actively listening, clarifying questions while maintaining a productive and inclusive environment.
• The Product Owner clarifies the 'why' and 'what' - prioritizing backlog items and acceptance criteria.
• Developers determine the 'how' - breaking work into tasks and forecasting capacity

Together, they form a realistic Sprint Goal based on empirical evidence and team capability.