In companies with a large portfolio of software or software-intensive products, functional overlaps are often perceived between independent products. In such situations it is ad-visable to systematically analyze the potential of systematic reuse and Software Product Lines. To this end, several do-main analysis approaches, e.g., SEI Technical Probe, have been proposed to decide whether a set of products with a perceived functional overlap should be integrated into a sin-gle product line. Based on the principles of those approaches we devised our own approach. One important property is the inherent flexibility of the method to be able to apply it to four different application cases in industrial software products at ABB. In this paper we present our refined ap-proach for domain analysis. The results and lessons learned are meant to support industrial researchers and practition-ers alike. Moreover, the lessons learned highlight real-world findings concerning software reuse.