Could you please add a sub-pixel brush like the one in Paint.net 3 5 11 or the brush in FireAlpaca where you can set the brush size to 1.5 pixels? It’s a very convenient and quick option for drawing clusters.
(In short, because the brush does not have an integer value, it can draw either 1 or 3 pixels per stroke, depending on how you move the cursor/pen.) 
