Use Action or Service when called in a loop?

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I'm doing a pose estimation with an ArUco marker on my robot. This is done to dock the robot. I have already the docking action and inside this action a pose estimation service is called synchronous within a loop. Is the pose estimation better suited as a action as it is called often inside the loop? But if it's better suited is it also possible to call the action synchronously?

The docking action is working like this but I'm wondering if this is the ROS intended style?

Thanks :)