Each activity should have a clear objective. In explaining the activity we can say how, but in itself an activity should be more goal-oriented than just how.
The model should be symmetric in its different dimensions. While it is more difficult to create, there are many benefits to it afterwards.
Feedback loops: everything should feed to defect management, and defect management should be the core feedback driver to all other activities.
Extended model for every practice ; could be formal (clear activities) or informal (hints about useful things to do).
