Complex sentence: One operation occupies the user completely, there is no multitasking, which makes NGOMSL inappropriate for analyzing tasks where the users are under time pressure, highly practiced and, in reality, do act in a parallel fashion.
Split into simpler sentences: One operation occupies the user completely, there is no multitasking. This makes NGOMSL inappropriate for analyzing tasks where the users are under time pressure, highly practiced and, in reality, do act in a parallel fashion.