This paper focuses on the work style in operation & maintenance (O&M) of information systems and discusses potential problems hard for involved parties themselves to find out. First, this study used ethnography to extract problems and critical factors common to O&M projects. Secondly, the author analyzed the work styles by comparing critical factors of contrasting projects. Then, the results of the analyses were shared with both projects. The sharing resulted in raising awareness that behaviors and values taken for granted by the involved parties could be where the problem itself or room for creative thinking lied. It was confirmed that practicing the analysis method used in this study could be effective for cross-organizational learning between O&M projects.