I carved the squares (on optimal) and measured the widths (up 1/32 from the bottom). All of the five carve region holes measured around 0.550. Not quite the 9/16 predicted but all the same size, proving that bit optimization, although selectable for these objects, has no effect.
The bitmap squares came in at
0.535 0.530 0.530 0.510 0.505
where the bit optimization is from none to best. I am sure results will vary from machine to machine but the trend should be similar.
Another wish list item: Please connect the bit optimization algorithm to the carve regions.