Best to use when
Needs, Wants, Desires is a Card Sorting exercise to help figure out priorities. It's best to use when there are a lot of feature ideas being thrown around when there isn't a good sense of which is the most important.
List outfeature ideas on Post-its.
The Facilitator should stand at the whiteboard and draw the flow.
For the first feature, add it to Needs if it is critical to the job to be done, Wants if it is supplemental to the main job to be done, Desires if it outside of the main job to be done. It is best to reflect on the Problem Statement while doing this.
Repeat for each of the remaining ideas.
Once all of the features are sorted, look at each section and the features in them and verify that each feature in is the appropriate section.