10+ years old yes it can be found at old saw mills. anything less it is not advisable

Wouldn't 10+ year old sawdust basically be compost? I was thinking fresher sawdust might be more like perlite as opposed to soil/compost.

Fresh sawdust will rob nitrogen from the cutting as it breaks down. I would not advise using that medium for rooting. You need something that is more neutral and stable.

I was thinking of sawdust as something just to hold moisture (as a perlite substitute or something like that.) I wouldn't think fresh sawdust would break down fast enough to need to worry about what would happen as it breaks down, particularly not if it were just used for a short period for just rooting a cutting. In other words, over the short term sawdust would seem awfully neutral. And a fig cutting while it's just rooting doesn't need nitrogen anyways, does it? What am I missing? It sounds like the bottom line is that it doesn't work, though. It would seem too easy for others not to be doing it if it did work.

You can root fig cuttings or fruit tree cuttings in sawdust because it is a short term use. I have rooted fig cuttings in sawdust. Here is my video or link to my video https://youtu.be/xue4vMBjgjI