The traditional academic way of making a painting entails doing many rounds of preliminary studies and sketches. Even those who were schooled in the contemporary manner like myself, where traditional methods and disciplines were downplayed, were still encouraged to do preliminary studies in preparation for final paintings.
But I have never liked working that way. After graduation from art school I would do a number of preliminary studies for a painting, but found that I aways liked the rough, loose studies over the finished painting. So at one point I decided that it was best to just sketch the drawing on the canvas... just do the studies there, as it were, and let what happened happen in the painting. I've never gone back to the old way. While I appreciate the discipline and craftsmanship that the traditional method involves, for me painting is very visceral and emotional process, and what I find is that the traditional way of working dilutes that process and guts the painting of energy.
This process even finds its way into my iconography. The traditional way that people paint icons these days is to draw the composition on a piece of paper and then transfer it to a panel, whereas I draw it directly on the panel from scratch. Even though icons are copied, working in this way gives my icons - for me - a greater sense of dynamism and vitality than working through different stages of transfers, etc.