How to tell if you need a Data Warehouse Assessment
A quick “self test” can help to identify areas of concern or need that may be the focus of your own data warehouse assessment. Use the self-test shown below as an aid to identifying your assessment needs:

Any question you are unable to answer positively, or any question to which you don't know the answer, represents a potential gap and risk in your project that merits examination. Interestingly, this same checklist and associated benchmarks can be used to validate readiness and completeness of planning for a new data warehouse effort as well as need for assessment of an existing one.