The “Update Interval” parameter, sets how often the Behaviour Tree updates. So an Update Interval of “3”, will only update the Behaviour Tree once every 3 seconds, therefore if you have a Wait action task that waits for 1 second, it will not matter since the Behaviour Tree (and thus the Wait action task) will only be updated and return its Status only once every 3 seconds.
Is your goal to update the graph slower? If so, I can add an option for that like “Update Speed”, but once again, “Update Interval” is simply how often the graph updated rather than how fast.