I've set our sprints up to last for 2 weeks, nominally 10 days.  Day 1 starts with planning and then moves to start development.  Day 10 has S&T and Retro, but also cleans up the release/tidies the Boards/backlog etc.It's now been suggested to me that a 10 day sprint should have 10 days of development, and then a deliberate 1 (or 2) day gap to be built in to allow the agile ceremonies etc.Should there be a gap?Or should the sprint also contain the ceremonies?
Should there be a gap between sprints?
agile;planning;sprint
There is no gap between sprints. After the Review and Retro, the next thing is the next sprint's planning. Now, what you describe doesn't sound like a gap as much as it is a 12-day sprint instead of a 10-day sprint. There is nothing inherently wrong with a 12-day sprint. The reason that most teams use 5, 10, 15, and 20-day sprints is because it puts the ceremonies on the same day of the week and it's just easier to keep track of.