Here is my workflow to create attractive procedurals materials with lower cost, directly in engine even if it doesn't integrate a Substance plugin.

 First, through Substance Designer I build very specific tileable masks and normals to create exactly what I need directly in UE4. In this way I use only six 512px texture.

 

2 are normals with RGB channels and 4 are only greyscale with 1 channel used.

Then I built the material in UE4 with 2 vertices paint and so many parameters exposed.

The first vertex paint allow us to put puddles where we want. Water infiltrate cracks first.

Then the second one remove cracks on road to bring aspect variations.

Finally I exposed parameters to change tiling, modify the wet bias or water height and so on