Windvane self steering can not cope with constant acceleration followed by slowing down.
When the boat accelerates to a significantly higher speed, the direction of the apparent wind changes. The windvane will steer the boat away from the wind, changing the total balance of boat and windvane.
The boat can then easily lose power from the sails and the system starts to steer back in to the wind.
This means that it may not be possible to steer an ultra light displacement boat or multi hull.
If you have a (very) small boat you may wonder if it can be useful to set up a windvane self steering system.
Usually that will depend on two things: The kind of sailing you do how windvane self steering compares to the alternatives.
If you never go sailing for more than two hours then for most it would be pointless. But if you always get too tired when you sail longer that 2 hours but you actually would like to go futher, then windvane self steering may be the ticket to Vreedom.
Generally not. Usually once the course is set there is no need to change the settings unless there is a change in the balance of the forces at work. The most important change you will have to make is for a lasting change of windspeed or wind direction.