It took me a while, but I think I’ve finally grokked the difference between type 1, type 2, and type 3 scrum. These different types or gradations of Scrum were suggested by Jeff Sutherland, one of the originators of Scrum. Briefly, the three types can be rather simply described as follows:
Type 1 – Fixed gates: Standard, out of the book Scrum. Plan your sprint, run your sprint, review your sprint – rinse and repeat.
Type 2 – Overlapping gates: Plan your sprint, run your sprint with ongoing planning sessions (for upcoming sprints), start next sprint as first sprint winds down, review last sprint – rinse and repeat
Type 3 – Mini gates: Plan a feature as needed & start sprint (features can start anytime), when sprint is complete – review it.
The way I see it, with type 1 Scrum, you are starting off with the training wheels on the bike. Things are pretty strictly regimented. We want to get the team used to a time box (they need to learn how to scope their work effectively). We want to get the team used to frequent planning and frequent reviews (put the rudiments of a quality driven, inspect and adapt system in place). And finally, get them used to working with smaller batch sizes.
As a team graduates to type 2 Scrum, they have mastered the fundamentals of type 1 Scrum. Now they can begin to improve on the process. Planning becomes much more of an ongoing activity that never stops. We remove the hard start/stop constraint between sprints. We want to establish a comfortable rhythm where the team begins to blur the lines between the current sprint and the next. We keep the sprint planning and review though – we want that culture of continuous improvement to remain. We probably have a trend of the batch sizes for each sprint starting to get smaller.
Finally, As a team gets comfortable with type 2, they have reached a point of really significant maturity. Now is the time when we can look at the team and say, “What if we reduce the batch size to one?” One sprint has one story. We overlap as many sprints as necessary. Basically we are creating a state of continuous flow where there are always multiple sprints in progress. In addition we have driven the batch size down small enough that the inspect and adapt cycle is now almost continuous. Sweet!
Based on my own experience I know that a team would have a very hard time skipping from type 1 to type 3. It’s an evolution. I also think that it is remarkably similar to other systems like Kanban – after a while I guess they all start to look the same in some respects.