If it is relevant to test the fact that the boolean is from a different value then in the first test, use two events.
Let's pretend your boolean variable is used to check the fact that a sprite is supposed to be moving or not.
Sprite.is boolean instance variable set (value = true)
-> Action move sprite
By default it would mean that it is not supposed to move when the boolean is false.
In that case you don't need to test if the value is false as the "resulting action" would be nothing.
Save yourself some useless tests.
But now, in the case the boolean stands for a direction (if it is true, the sprite goes right, if false, it goes left).
Condition Sprite.boolean instance var is set
-> Action Sprite go right (Sprite.x = Sprite.x + 60*dt)
Condition Sprite.boolean instance var is not set
-> Action Sprite go left (Sprite.x = Sprite.x - 60*dt)DT tutorial