ArtStation - Roof Tile Texture – Complete Workflow From 3D Modeling to Photoshop

I will start with a simple roof tile, and lay it out in a tileable pattern. I then create variation by duplicating and tweaking the original tiles, and randomizing each tiles position/scale/rotation.
Next, I fix any overlapping errors by hand. Once my high-poly is finished, I bring the baked maps to Photoshop, and use a combination of photo sources and hand-painted details to finish the texture.
Workflow
If you are familiar with other software, such as Zbrush and Substance, you should be able to integrate them in different parts of the workflow (for example, you can leverage SD's procedural tools to create masks, and Zbrush to sculpt the individual tiles).
This workflow can be used to create all sorts of textures: Sidewalks, stone or brick walls, tile floors, you name it.
This is how I create most of my textures for Overwatch, and the goal of this tutorial is to teach how to make hand-crafted textures like this.