Why a refined top matters
Sprint planning is fast when the top of the backlog is ready — slow when it isn't. Refinement is the work that makes planning fast. The Scrum Guide doesn't prescribe a ceremony for it (it's a continuous activity), but most teams hold a 30–60 min refinement session weekly.
Definition of Ready
Many teams adopt a Definition of Ready: criteria a backlog item must meet before it can enter a sprint. Common DoR: clear acceptance criteria, agreed estimate, dependencies known, designs (if needed) attached, no open clarifying questions.
↳ the over-refinement trap
Splitting large items
A 13-point story is a warning sign. Split it. Common splits: by acceptance criteria (the AND in "must do A AND B" is usually a seam), by user (admin path vs user path), by happy path vs edge cases (ship the happy path first, add edge cases later). The split should preserve user-facing value at each step.