By the way I did consider experimenting with a soft shadow, but that turned out to be not as good as non diffused lighting. I suspected this, as sharp lighting seems to be used in art reference books for this sort of thing. Noting beats learning though doing.
And of course a square combo for instagram / job contact sheet.
The setup was mostly a top center flash with honeycomb. But of course each shot had specific fine tuning, like with a front softbox and speedlites at various angles. Tethering into Darktable. Incidentally, I figured out two things: 1) portrait orientation gives uneven horizontal exposure, as this became visible when everything in the scene was symmetrical; and 2) when correcting for whitebalance in post, tune to the second histogram peak rather than the first peak.