Thanks for necroing this and posting the cargo formula...I was wondering how that worked! Essentially the formula includes a wall thickness for cargo blocks of 0.25 that is not considered useable for cargo storage.
To distill it down to more practical usage I created a little table to show block size versus cargo utilization (percentage of volume that is actually adding cargo storage)
Cargo utilization table:
Block size: Percent utilized:
1 12.5%
2 42.2%
3 57.9%
5 72.9%
10 85.7%
100 98.5%
As you can see, the smaller the block size, the larger percentage of the space that "wasted". If you built a single 100x100x100 cargo bay it would use 98.5% of the space for cargo (very efficient). If however, you instead built 1,000,000 1x1x1 cargo bays (same total volume), it would only use 12.5% of the space for cargo!
Going forward I'll be targeting cargo bays with a block size >5 and avoiding any cargo blocks with a size <2 at all costs!