P.S Where do you source your textures from? Custom scans or any good web resources you can recommend?
I missed this edited addendum so here's answer now :- ).
Everywhere. When I get compulsive moment I just browse through every nook of the internet. Here are some of the best sources imho:
-Textures.com Yup, everyone knows about it but in past year they added 2 really interesting sections. The scanned materials and allegoritmic substances. Both are really nice. Currently it's together less than <200 mats but lot of them have interesting maps.
-Allegoritmic source - Great repository of substances. They are hit&miss but it's obvious from preview which one it is. The partially scanned ones (like fabric) are fantastic, the 100perc. procedural mostly trash.
-Megascan - I am little bit jaded about this one, I paid 8k membership since last yeah August and so far use very little of it. They are so slow (two rocks each month, thanks...)...and scan so much (literal sometimes) trash. But lot of it is useful and the vegetation is invaluable.
I don't use Substance Designer or Painter (yet) btw. I just use them as tiled maps.