Listening to Mark I hear my own teacher, who was taught in Australian Tonalism - the Max Meldrum school. I fall back on those disciplines all the time. As someone who had sketched and thought in lines, it taught me to see and paint.
However, more recently after enjoying the accuracy required for portraits I've enjoyed digging in to more detail in landscapes. I've found the key disciplines of capturing the tonal drama, bringing the whole painting along together, painting from the edges, etc. It's all there telling the story behind the details. Lose that and lose the painting.
I'm an overseas aid worker, so have been painting over two decades but only completed about 20-25 paintings and only 8 originals.