[zubspace]

Things get interesting when the number of possible code paths increase. One such beast is the Unity Standard Shader. There are dozens of combinations depening on Metallic/Specular PBR, Multi-Texturing, Shadows, Light Types, Light Baking, Forward/Deferred Rendering and so on. Combine this with different backends (OpenGL, OpenGL ES, DirectX, Vulcan) and graphic card abilities and at some point adding new stuff gets quite complex.

I guess they simply throw money and play testers at this problem. (Unreal probably more so than Unity) But how long can you scale this up?