To make an impact on the design in usability testing, the test tasks are essential ingredients for the early system development process. Complex design problems are not solved by focusing on the details of a prototype and setting the scope on what is already known by the design team. Instead, the design value of usability testing is increased by deliberately relinquishing the assumptions made and implemented into a design. In the development of complex systems, usability testing with  extended scope and open-ended structure, as presented in this paper with three empirical cases, delivers not only specific knowledge about the user interactions with the system, but reveals issues that, despite rigorous user research efforts, have been overlooked in the preceding phases of system development. Therefore, we suggest applying open-ended usability test tasks for testing systems in complex settings such as in the development of health care systems.