I just recently discovered the impact a sketchbook can have if you use it to experiment and not as an end product, though I most often use something from my sketchbooks as an end product. But by taking away the pressure and I guess I am just a messy painter and my process which is often total chaos which eventually, by cutting and taking away things, will turn into interesting illustration.
I remember in high school I didn't understand this specific process that I had to go through and by looking at the clean and beautiful works of my peers, made me give up. But I have learned, maybe especially through life (deep ;)), that when I persevere; almost everything will turn out worth looking at.