The short version
If your next defensive action is unavailable, you have already spent too much.
Keep one answer in reserve
Attacking, defending and dodging all compete for Stamina. Stop your output before the bar is empty when an enemy is still able to act.
Practice with no damage goal
Spend one encounter only on Dodge timing, then another on Block. The point is to make defense feel available before you mix it into a full rotation.
Build around the rhythm
Heavy frontline identities can value Stamina efficiency, while faster identities can use movement to create safer windows. Exact costs and values still require EA verification.