I did this test to show the difference between a half hour test , 1 hour test and 4 hour test. To see the accuracy between them, and the compass was showing the difference only. a half hour test was 20 degrees less accurate then a 4 hour test. Altho the shadow stick shows general direction, so a half hour test may be all one needs. So to sum this up, the longer the test the more accurate it is ,
