If you deploy the wall and mash the button to cancel it, the next times you cast the wall it can deploy instantly instead of waiting for input. You can get out of this by mashing cancel again on a later cast (which you'll often do because the wall deploying instantly is usually not what you...
+1, also other items with expiring stacks (Berserker, Escalating Resilience) don't work this way - you stay at max stacks as long as you keep meeting the condition to gain new stacks.