During the design of class models for information systems, databases or programming, experts of the domain and designers discuss to identify and agree on the domain concepts. Formal Concept Analysis (FCA) and Relational Concept Analysis (RCA) have been proposed, for fostering the emergence of higher level domain concepts and relations, while factorizing descriptions and behaviors. The risk of these methods is overwhelming the designer with too many concepts to be analyzed. In this paper, we systematically study a practical application of RCA on several versions of a real class model for an information system in order to give precise figures about RCA and to identify which configurations are tractable.