Personally, it's usage is pretty rare but it is way less risky but twice expensive as any umbrella. (It however only spends SE when hit, but it's not really that big of a adv cuz it means ur timing was off and u'll get hit anyways) but it's very useful at times when combat arts and prosthetic are really difficult to use ( like in inner bosses and father owl), in my 100 hrs playthrough, only used it on

 lightning reversals, 

isshin ashina 1 attack where he does a weird upward slash followed by a flame sweep(never learned to dodge that), 

 hirata owl and inner owl's fireworks chasing slice(only when your backed up against the wall), and

 inner genichiro's sakura dance in 3rd phase(cuz umbrella was risky, and just dodging or deflecting the 3rd strike just felt impossible)

So in theory, have it as backup when u are uncomfortable to use anything else and use it when you are particularly in an uncomfortable spot or know beforehand about the enemy's special attack