Zigzag is a lagging indicator. It might look great on a historical chart and it fools you into thinking you can trade those signals. In realtime it repaints a lot.
So the best way to use it is if you have a method that gives you a entry opportunity after a swing on the zigzag has been really printed and confirmed.
On those zigzag semafor indicators , the buy / sell signal is when you get the confluence of 3 zigzag swings on the same spot. In order to confirm that it won´t repaint, you have to wait until at least a 3rd swing is printed on the indicator. And that is not even a guarantee because the slowest zigzag has a big leg.
Run the indicator on the strategy tester in visual mode and you will see...