I rarely use scrim myself, (although I am trying to change that).
The reason for my lovely rows of painted scrim is that I cannot bear to throw away any of the bits of the paint left over from when I paint fabric.
I did start off by soaking the paint into kitchen towels for use in sketchbooks and mixed media pieces, but that pile has become so large and I cannot bear to throw any away because the colours are all too wonderful.
That's when I hit on the idea of using scrim and now nothing gets wasted, and the mixes of different colours at the end of a painting session creates pleasing results.
When I have a big enough collection I lay them out like this and make co-ordinating bundles, that I hope people will like.