Exactly!
This is why when Shiliew got his DF, I was shocked at people calling it useless! Cause it's not
Having observation doesn't guarantee you to dodge the attack correctly in the right timing even!
You need to have great observation, speed, FAST reflexes and reaction all to dodge JUST one single attack!
How about a fake attack, or consecutive attacks, or a barrage of attacks! It is a very taxing mission, very exhausting, where your sixth sense need to be on point throuhout the duration of the fight!
I'm happy Oda proved it this chapter, so that people stop shitting on Shiliew's DF or Sanji's invisibility saying "it's useless with observation"
Cause it's quite the opposite, observation is useless if it was NOT good, and your reaction and speed on freaking point all the time