6 arrows that follow a spline via a Align to Spline Expression that should also point to the red sphere via the Target Effector. All Expressions have the same priority. Since the arrows’ Expressions are executed prior to the sphere’s Expression, a synchronization gap results. If, for example, the top Null object’s Shift Priority tag’s Shift Priority value is set to 10, all arrow Expressions will be executed AFTER the sphere’s Expression and the arrows will all point towards the sphere.
The Shift Priority tag only works on Expressions. Generators and Deformers will not be affected.