Hi! This is hard one for me to explain properly, so I'll just use an example. Just fire up Photoshop, it's the default brush behaviour. Unfortunately Photoshop is one on the only applications that has this mode, which is the sadly the main reason I haven't been able to move away from Adobe. Black Ink seems like a perfect fit for it though, still in beta and boldly digital, not trying to emulate real brushes. Very digital brush behaviour like this should fit right it.
One of the left is Photoshop, one the right is Black Ink. Key points being the ones where the stroke overlaps with itself. Strokes are light (20-30%), with Wacom pressure sensitivity mapped only to opacity and color being pure black. The Photoshop brush makes flat shading far easier as the single brush stroke doesn't turn into more opaque as it crosses itself within the same stroke. For a single stroke, it takes the highest pressure applied at any given point, not the total sum. Separate strokes will add up just like they do everywhere else. The lower one is made by gradually increasing pressure throughout the stroke. I've tried to emulate this by mapping the Wacom pressure sensitivity to color, which goes from white to black, but it doesn't really work.
I know it's stupid to ask one software to be like some other, but I'm really disgruntled about the subscription only model introduced by Adobe, so I'm trying all my options to get away from them... Also, layered TIFF would be good save format for integrating Black Ink into production pipelines.
Disclaimer: Haven't bought the beta yet, waiting to see if this is greelighted as I'm seemingly unable to live without it. :P