The challenge, in a nutshell: if a dedicated system is built according to predefined principles and use scripts, in the first versions of a generic system, it cannot always be known who the main users of the system and what the common use scripts will be.
One of the challenges in the user experience field is the great difference in the character of products. There are systems whose users will be defined at the beginning of their development, along with their use environments and use scripts. I define these as dedicated systems.
In an operational system installed in an armored fighting vehicle, users and uses that are known in advance are characterized. When a CT system is being designed, it is obvious who the user segments will be, and in the characterization of applications such as Waze, developers have a good general idea about who the users will be, what ...