I've noticed that there are inconsistencies on how different trail clubs mark intersections or direction changes. In Georgia and NC, I have found that they are generally done the way I understand to be correct; at an intersection where you go straight, a double blaze with one directly above the other, and if the trail turns to the right, the upper blaze is offset to the right - and if the trail turns to the left, the upper blaze is offset to the left.
But north of Damascus, the double blazes for when the trail turns (at an intersection), the double blazes aren't offset, but simply put one above the other.
This led to a bit of confusion some places where the trail came to an intersection that wasn't obvious where to go, I had to hike a while looking for the next blaze... when I didn't find one, I had to turn back and look again. The places where the trail simply turned (not an intersection) it wasn't really a big deal, since there wasn't a "wrong way" to go... but shouldn't all the trail clubs along the AT use a standard marking format?
The reason I'm posting this is as much to suggest trail clubs follow a standard format, as it is to let new hikers know to be alert and attentive when coming to double blazes.