You can set the tube height to like 4mm and that's pretty much what you'll get.

The tubes only need to be tall enough for a "window" at the bottom and a splitter in the middle so that plastic will flow up one side and down the other.

The window height calculations are automatic right now. To make sure the window area is as large as the tubes so it doesn't create a bottleneck that stops flow.

But if you print tiny tubes with a tiny nozzle you could probably get the tube height down to ~3mm.

There's binaries if you want to play with the settings and see it for yourself

I had the same thought -- with a checkerboard pattern of 1:1:2 "brick" voids where each brick would be surrounded by bricks of a differing offset, one could conceivably calibrate the injection step and the print might have less propensity to cleave along xy planes. But, given the complexity of that calibration (and need for a high-flow head) I'd rather use the brick infill available today.