PRINCE2 distinguishes between management and technical, specialist products. The first are “value enablers,” the latter drive the real value for the customer. Both are needed — assuming the right balance, but it is technical products that build the project’s backbone.
There are companies where extensive control processes diminish the clarity of the value for the customer. The key aspect then is the organization’s project lifecycle — its phases determine the key dates for the project.
In such organizations milestone plans — the ones based on key technical deliverables (groups of deliverables) — are a rare thing to find.
When developing the scope, building a WBS, and later on — continuing with a schedule, we should still create a milestone plan, presenting the completion of key technical products (not project lifecycle phase gates). Such a plan is particularly useful when reporting progress and when discussing the project with the organization’s management.