More patches do not always make a better profile. If the printer is absolutely linear, then more patches should be the same as fewer patches. The Z series should be fairly linear, so more patches may or may not make much of a difference. Where the big gains would be made are in the firmware, this is where the change from RGB (image) is made to the CcMmYKkkkRGB. As far as the "depth" of the blacks, that's all up to the ink and paper (assuming the firmware and ink limits are doing their job).
If you are looking to measure accuracy, then you will need a handheld spectrophotometer as there are no utilities to use the spectro built into the Z series printers (yet).