Spaced armor is only really useful for limiting the effectiveness of explosives, which now have proper line of sight for their damage bubbles, and then the spacing still needs to be somewhat extreme to be totally effective, increasing the weight of the supporting framework. What's more interesting and technically complex is the actual methods of layering armor. This is more complex than you'd think since Oninum has a weak enough SI that you can't stack two plates of it on a beam with a long bolt like you can with other armor.
It's also important to consider that the voxels themselves ARE a part's hit points, which has damage modelling implications I'm still grappling with while we continue to find out more about the mechanics. So, contrary to my original assumptions, striking armor on an angle does stop more damage because it puts more voxels in the way, but we don't have any bounce mechanics, so it's much simpler than something like Warthunder.
There're also plenty of reason to avoid over-armoring something. Fighters and light gunboats can use the top end of the speed scale to avoid damage by creating a large lead for attackers to aim at, meaning in-flight maneuver and speed retention will be at least somewhat important in a fleet's doctrine and tactics.