Hmmm…
I would say its pretty strong and can last long hours, but it depends on the environment you are in.
Or what you are expose to that needs shielding.
And in my opinion it compunds with the passing days but not in a way to make it permanent but to last longer in the day +
If you have KQ play it x 1 AND THEN a couple of loops can last 2 or 3 days.
Just read the KQ so you understand how to build momentum with KQ to get to a point of long lasting effects for other fields with less loops