When I Paint I tend to use blocks of colour and hardly any outlines. But when I'm sketching, for quickness I like outlines as well as colour.
I love the quickness and brightness of ink. I try all sorts various pens and brushes. I am currently experimenting with a caligraphy brush pen. When I say 'ink' here I don't discriminate between bottled ink, pens, waterproof or otherwise - it's usually about a way of being able to sketch quickly rather than about the final drawing.
I do sketch quickly (some might say scribble!). Though not as quick as some of the videos I've made as they are speeded up to show more of the process.