[scyzoryk_xyz]

Yep. I think a better comparison in our modern world would be the film studio. Painting was something you were taught in a rigid controlled environment and the materials and knowledge how to use them wasn't something you had the freedom to just easily use on a whim however you like. You were taught an entire language and way of thinking by your master, most likely from a young age.

Our modern reality makes it truly hard to imagine how these people thought because we are so used to photographs and images being cheaply reproducible and widely available on screens. A painting used to be something that was located somewhere and you had to travel to get to see it. If you owned a painting, you had this unique privilege of being able to show it to people in your own context. Works of art were incredibly powerful status objects, capable of sending the right messages about your pedigree, about your wealth and power.

What you describe with the prefabs I think gradually came along later, as painting became a more common trade and even the middle-classes started being able to afford to have them made as objects of status.