For some people the sketchbook may be the finished piece in of itself, whereas for other artists its a means to an end for the larger project or just a place to doodle and experiment. There's no right or wrong with a sketchbook, which is why I love them so. I wonder if young people feel more pressured to have a pretty sketchbook than older artists, because of this feeling they have to get things right and perfect, and that they have to share it online for all the world to see, whereas older artists are less self-conscious and less likely to feel they need to post every single doodle or thumbnail on social media.
I realize this is an old video, but is there any chance we could get a direct link to see these sketchbooks? I'm having a lot of issues with the general search interface at Tate Britain. Is there anyway to see a list of the sketchbooks by artist?