Here is a timing diagram example. The state / condition notation shows states as a list next to the relevant participant. A state-line is then needed to show what state a participant is in at a given time. Unfortunately, if a participant has many different states, then the amount of space needed to model a participant on the timing diagram will grow quickly.
The general value notation fixes this problem by removing the vertical list of different states. It places a participant's states directly at the point in time when the participant is in that state. Therefore, the state-line is no longer needed, and all of the states for a particular participant can be placed in a single line across the diagram.