From my own experience, mature fig wood does air-layer
much, much, much better/quicker than the green wood...
Another down-side about green-air-layering; once you think
that the twig is well rooted (it takes longer), and then 'cut' it
and pot it up, most likely the whole thing just 'rots' up.
I have recently lost such-things, due to my push to
reproduce a precious plant.
Yeah, stick to brown wood.