Hi - bumping this - anyone out there with advice? 

Sawdust may be incorporated into your soil as mulch but you should compost the sawdust first before applying.

 If it is incorporated, an application of three to four bushels for each 100 square feet of soil is suggested. The reason you should compost your sawdust first is because soil microorganisms may deplete soil nitrogen levels when breaking down the sawdust.

Here is an article from Penn State Extension with more information:

https://extension.psu.edu/soil-management-in-home-gardens-and-landscapes

Thanks so much. I guess my question is really whether aging the wood shavings, as in having them sit outside as a mulch cover for a number of months, is practically akin to composting. And I’m assuming you’re saying it’s not? I know with leaves I’m a-ok using them as fall mulch, then turning them into the soil the following spring …

That is correct. You should try to compost the sawdust  prior to adding directly to your soil.

The same is true for leaves. It is best to compost the leaves with some green material before adding leaves directly to the soil.