The timeline feature in Unreal Englineis useful as it can serve many functions such as animations for doors or ambient effects like flickering lights or animal animations like snakes. It can also do the animations in different ways, such as a smooth acceleration movement for a swiveling door as opposed to a constant speed movement of a sci-fi sliding door.
They are also useful as they can provide multiple outputs at the same time which are always syncronized.
There are also multiple ways of setting up the lines which change how the values are affected over time.
Sam Davis 