After quick sketches have determined the artistic direction, the first version of an in-game effect should concentrate on establishing the rough timing and duration of the effect. Depending on context, the overall effect may consist of a single event or a sequence of several events, each with their own timing.
The source of the effect can help to determine this timing. For a traditional weapon flash or explosion, particles in the range of 0.1 to 0.2 seconds communicate the speed and power of the event. Smoke, gas or dust particles can linger for several seconds or longer. It is useful to stagger the duration of each element so that the user has time to digest each important part. A slow plasma build up with a fast release, an extremely fast pop with leftover dust and a slow, oozing steam all establish types of feedback for the player.