Sketching, drawing and painting the human figure directly from life is a valuable discipline. Our understanding of shape, proportion, volume, scale, foreshortening, light and shade can be challenged.
Given that these principles are also relevant to any other theme, the figure is a worthy go-to subject for all-round drawing and painting practice.
I favour line and wash for making quick figure sketches while out and about because it’s so versatile, lightweight and portable. This quality makes it equally effective for more resolved studies when time allows.