In principle, all the business requirements of a model can be built only in Cognos TM1. However it’s possible and sometimes desirable to use other tools of the Cognos platform or tools from a different vendor. In the below mentioned picture, the main components of such a solution are displayed. The red components are the Cognos TM1 components. The green ones are the additional that in some situations can be used.

Most important:
No matter what tools you use, they should support you in doing your business more efficient and effective and should gain you money.