focus of sketching/ perspective

During high school, I went through a lot of drawing classes. Most of them really focused on mastering value, drawing still life images, etc... and almost everything we did was entirely in graphite. More recently I've been focused on trying out new ways to draw and new media (hence the sharpie!). And I've also come to care less about the drawings being "perfect." I rarely erase when I'm sketching, and I'm less concerned with making neat, exact lines and more with capturing the essence of what I'm looking at and communicating angles and proportions. And speaking of proportions, I added this image of a 2 point perspective drawing because it's really evident how each vertical line connects to each vanishing point. I think in this drawing it's really easy to see how the technique creates depth.