Multi-flash mode is mainly for stroboscopic effects: firing several flashes during one exposure so a moving subject appears multiple times in the same frame. Typical examples are showing stages of motion, such as a golf swing or other continuous action, or creating special-effect images.

Beyond that, it is generally not one of the most useful speedlight modes for everyday photography.

If you try to use multi-flash with multiple off-camera flash units, timing can become an issue, since slave flashes may not stay perfectly synchronized.