It is funny I used to peal 2-3 inches girdle on the branch and by accident the girdle was onlt 1/2 inch but the wet moss covered that part plus almost 3 inches of the branch on the top of the girdle. I found no difference in rooting both ways developed good roots. I made some research and found that it makes since the size of the girdle makes no difference. The girdle function is to prevent sugar and carb made by the leaves on the branch to travel to the main root but to gather at the cut and above of it to make new roots. But the important thing is to cover enough of the branch by the wetting materials to have sufficient roots.

Another observation if the airlayered branch has one fig it grew bigger than the rest and got ripened and very sweet. Again it makes since that fig got spoiled by lots of suggar and carb made by the leaves and could not pass through the girdle to the main root.

I am not an expert but learning by trial and error and it works for me.