"It might take you 20 years to write your novel, but put a sentence or two on a page every day."

I think this is the wrong advice. Writing a novel like this will give the impression it will never be done. If, after ten years, you'll read what you have so far, it'll be sh.t because, in ten years your style and your way of thinking will change a lot.

My current idea is, if you want to achieve something, focus and do it quickly. Otherwise you will run out of steam and finally be frustrated. Being frustrated a few times results in the impression that you cannot get anything done.