How long does Hayato Suden Strike debuff last?

How long does Hayato Suden Strike debuff last?

Is there no way to increase Hayato movement speed during Shinsoku?

Sudden Strike lasts for 10 seconds. And no, Shinsoku is fixed at 70% movement speed.

Ok thanks.

By the way, is it Rai Sanrenzan always win Shinsoku unless you cap? Also, is it worth using 8-skills combo to get 8% attack in term of DPS on boss, because it seems to me I can use 8 times of Rai Sanrenzan during the activation of the 8-skills and the attack buff last so short.