In this case, i think it’s just the height blend that gives the illusion of smoothness.
The better the texture used for the blend, the less you notice the blotchiness factor.
If you use no blending and solid cloros, you basically get hard lines everwyehre, circles too.
Under the hood, each meter ends up being a pixel.
If you try and export the painted layers you should see that.
Like I said, you can use the same texture as teh red material in the height blend of the other, and get slightly better results.
Also do make sure the layer data you created is the correct tipe while at it…