I want to use Sprytile's paint tool on pre-made meshes, but can't find a way to split faces into equal-sized grids. I'm aiming to achieve texture-stretch-size consistency in my models. Is there a way in Blender to do this?

Select the edges that you want to slice, press Ctrl + E and select subdivide. You can scroll up or down to set the number of cuts, or set it in the tool options.