Information below is from „Do Better Scrum“ – special tips and insights. You can download it from http://www.scrumalliance.org/ I just want to use it for references in my posts 🙂
This meeting is not mentioned in some of the Scrum literature, but is essential if you
want to achieve a continuous flow of the most valuable done features from your
During every sprint, the product owner convenes one or two meetings where the
Scrum Team and, if required, other stakeholders, meet to size backlog items that have
been added or re-size large items that need to be split into smaller ones for tackling in
the next sprint or two.
Teams need to devote 5-10% of their time during the sprint to preparation for
the next sprint or two. The estimation meeting described above is an
example. Other examples are story-writing and release planning workshops.
This is important to avoid a stop-start effect at the boundary of every sprint.
The other implication, of course is that teams should spend 90-95% of their
time doing the work of the current sprint!