Gallops are done when a 16th note (other notes like 12th and 32nd notes have been used, depending on the beat) precedes or succedes a 4th note or an 8th note. It is named as such due to both feet acting like a galloping horse.
Gallops can add difficulty to a chart by confusing novice players that they may look like jumps, or when a sequence of gallops forces a player to do a crossover or a spin.
Examples of Songs with Gallops[]
true... (trance sunrise mix)
Rhythm & Police (K.O.G G3 Mix)
Tsugaru