Déjà précisé dans le post initial : yn568 ex2

Il n'y a que ça comme info dans la notice du yongnuo 568 :

High-speed continuous shooting
The flash can realize the high-speed continuous shooting function. Please set the camera in the continuous shooting form and then shoot.
Please note: The number of photos that can be continuous shot is related with the output level. Please use the fully charged battery.