Work break down structure is basically tool used to help schedule,cost estimation and human resource management by breaking down a major work into various small work or thing that will be required to complete the bigger task.
Various pitfalls seen commonly are
1. Neglecting to create a WBS Dictionary
2. Expecting More than 100% from your WBS
3. Why bother with Formal Change Control?
Any update to a WBS, other than an elaboration of details that already exist, should require formal
change control. To ignore this step invites changes in scope that can spell doom for the project.
4. Adding Requirements in Lieu of Tasks
When you place a deliverable on your WBS, you can break down the deliverable into the activities required
to create it. What doesn’t work is breaking down the deliverable into the requirements that describe it.
Deliverables and tasks do belong in the WBS, but requirements do not.
5. Too Many Tasks