I am learning Blender and currently building a simple low poly model. Trying to follow reference picture I realize that it is very difficult to build a model such that all faces are perfectly planar. I can use flattening tool but some quads are never brought to perfect flatness. When tested wih 0.1 deg limit they show nonplanarity.
Even when I scale one face of a standard cube (in its own plane) it is enough to show nonplanarity above 0.01 deg. Similary scaling and/or rotating simple plain is enough to create nonplanarity above 0.02 deg.
I am guessing that this is related to the finite accuracy of numerical representation of the location of vertices. Clearly it makes sense to disregard this level of nonplanarity.
But how about 0.1 deg? 1deg?