Textured supports

Konstantin Westchilov (Russian), Rocky Coast.
Some of the art auction houses have zoomable images of the lots. This allows you to see the brushstrokes up close, and is very instructive. By looking closely at the distant cliffs, this painting looks as if it's been done on the rough side of masonite; a texture I find distracting. I prefer the look of canvas. But Westchilov seems to have applied the paint thickly enough to cover it.
As a general rule, the thickness and texture of the paint should be reduced from foreground to background. This helps create the illusion of distance. The distant cliffs in this work have been painted thinly and this is where the texture of the support is quite visible, to the point where it becomes a bit of a problem (see cliff in bottom detail). There are some paintings where the artist has deliberately chosen to express the texture of the  support, but this is usually in an area of the painting where is simulates the weave of fabric in clothing, for example.
Some say that masonite contains acid and eventually degrades, potentially destroying a painting, but perhaps it depends on the manufacturing quality. The more thoroughly the masonite is primed the better, to create a barrier between the oil paint and the wood acids in the masonite.
I love Westchilov's brushstrokes in the waves.