This process might have started when Arlo really got in to the lean literature and looked around for waste in the Scrum system. He believed he found it in estimation. The amount estimated to work always differs from actual amount worked, is therefore supposition and only a guess, so this estimation was declared muda. There are a few different references on the matter, including Dave Anderson, Mary Poppendieck, or Amit Rathore. Even NetObjectives weighs in with a course offering.
The idea of the variable length Product Backlog with the need to reorganize priorities and estimate size was replaced with a fixed-length queue placed on a whiteboard for the Product Owner (Customer) to fill with Minimal Marketable Features (MMF), or what in Scrum would be User Stories. The length of the queue is seven, as this is believed by Arlo to be about the maximum amount of items any one person can hold in their head at a time. The slots are marked with permanent marker. Since the Product Owner trusts the team to do the work, the team believes these features to truly be: minimal, as anything less would not be marketable, which has immediate value for new or existing users.
The customer is allowed to rearrange these 7 MMFs as often as is seen fit. When the team is ready to pull a new feature, it is whatever is currently at the top of the stack. The 7 MMFs must fit to one of two goals on the board. When entering a new feature, the customer determines if the completion of remaining MMFs in the queue would satisfy the goal. If so, a new goal can be added to the board and if not, another MMF to satisfy the goal is added. There is one expedite slot for the customer to override WIP, anything else has to wait for a slot to open.
Releases can occur any time any one MMF is finished, as there is an ability to hide Work In Progress on the production site. The customer also has an idea parking lot for the overflow from these 7 items, or for other goals. An approximate wait time of when a feature may be released is added to the bottom of the board. MMFs are dated when they are placed on the board, and when they are finished to derive the average time of a feature. Significant changes in the size of work which effects throughput trigger a recalculation of this lead time. Arlo calls it the “approximate Disneyland wait time”, and is a statement such as, “Your expected wait time today from this point is between x and y days.”
The engineering team has 4 slots for WIP. This was determined because there are 8 engineers who pair all code. A majority of the board is reserved for information related to the work. This could be an article on competitive analysis, CRC cards, an individual engineers task list, or anything else deemed interesting to the work at hand. Stand-ups happen multiple times per day and are short. When the team switches pairs they ask if there’s any significant increase of information of note which is not on the board.
The amount of information for a task crescendos and then as it starts to taper the customer is asked if this meets expectations. Sometimes the information arrival increases again after that, but then the information stops coming in and all tasks are complete and the customer is reviewing the MMF on the production machine. Every Friday is a trade show of all released MMFs, and is a very jovial time in the office, a celebration of a job well-done.