After several attempts, I've finally arrived at a style which pleases me--one which isn't too detailed, but also not too flat & one that approximates the look of beaten up wood. I've considered a result that's a bit cleaner; with less wear and tear, but I've spent enough time on this and am eager to see the entire result; otherwise, I feel as if I'll be in texture painting limbo.

 All of this was painted on a single layer, which is less ideal for making any edits prior creating the various other maps in Materialize, but all previous attempts painting on multiple layers felt too cumbersome and perhaps it will be good to see what I can squeeze out of Materialize without the benefit of tweaking individual layers. 

 A Practical Approach to Physically Based Shading in Unity -- This link contains some basic information and value charts for metallic, specular, & diffuse properties of various materials. The last half of the article demonstrates the importance of such things on a crane asset in the Viking demo scene; particularly the importance of SecondaryMaps to add detail at a relatively low cost.

Regarding the CrateA asset, a specular smoothness/roughness map may not be required and a simple value may suffice, but that remains to be seen depending on the nails/spikes & perhaps other unforeseen added details in the diffuse.

There were a few issues with the UVs that required some manual stitching, and in doing so, I did a manual repacking. UVPackMaster still has it's place, and I think with a more detailed grouping the UVs could be grouped a bit better. 

Despite not doing any traditional texture baking, it's always good to remember how normals will be rendered. This video demonstrates problems and solutions when baking normal maps as it pertains to UV layout and smoothing groups.

First Pass & Problems

Solutions

CrateA is currently adopting the first solution, which is to say it uses face weighted normals and split UVs accordingly. It'll be interesting (and perhaps problematic) to see how a painted and/or diffuse-generated height map can be used to create the normal map in Materialize.

More Normal map info

Types of Normal Maps & Common Problems

Toolbag Baking Tutorial -- The last 25% has some advice for tips, tricks, & solutions to common problems.

 Initially, I had started painting the diffuse, but it seems more prudent to first paint a height map to get a better understanding of the normal map

 It occurs to me that perhaps I should allocate some empty space on the UV sheet to account for the possibility that I may later discover a need for more crate-related objects. I suppose that illustrates the importance of the pre-production phase, which I've more or less bypassed in the interest of making some new art. 

With minimal effort, I was able to find a better packing. UVs are grouped by face numberings whose faces are colored accordingly for illustrative purposes.