What’s a substantial period of time? Like a gallop?

Edit: they only gallop when babies but their trot can have no points of contact

The key finding here is that they trot which includes a suspension phase. Elephants for example trot generally only as babies and reportedly sometimes downhill as adults.

https://www.cnn.com/2024/07/04/science/hippo-airborne-study-scli-intl-scn#%3A~%3Atext=The+team+also+found+that+hippos+almost%2Cto+a+gallop+depending+on+their+speed.