On the first day of a new painting class, when I was a student, the teacher denounced the way I held my brush; as if it were a pencil. He proclaimed one should always hold the brush as if it were a flashlight, hence the entire arm is involved in painting. A very good point, although I frequently use both ways.
Brush marks are affected by a number of things, such as the actual brush, painting surface, and paint. At the same time, their application should ideally be fluent and second nature; something I've often found myself struggling with. The brush marks in the above painting, oil on canvas, 16 by 12", were deliberately made softer than my usual approach. While planning in advance can result in a form of harmony, only experience will ultimately lead to a flow that mimics hand writing for its ease and personalization.