I have used Architect as the main source of Impromptu catalogues , Cognos Query packages and Transformer models.
Basically the Data flows through Architect,then through the 3 Cognos applications.We used this approach to minimise duplication of changing new data.
We produce 6 different Impromptu catalogues so when there is a change in the database, we only need to make the change in Architect not in all the other places.