When it comes to writing, quality and quantity do not precede consistency. Come to think of it, that probably applies to a lot of things in life. Running is more beneficial when you do it every day (consistency), than when you do it for quality (running for speed) or for quantity (running for distance).
For example, running at a moderate pace for 20 minutes a day (consistency) is more beneficial than running at top speeds for 30 minutes a day (quality) because trying to have the quality of speed will wear out your muscles and cause you to become injured. Writing for quality is usually a SLOW process of meticulous self-editing to get all the words just right the "first time around." (i.e. impossible). It will wear you out and injure your creativity.
And running at a moderate pace for 20 minutes a day (consistency) is more beneficial than running slower once a week for a couple of hours (quantity) because you may burn out before the two hours are up and your body has a hard time remembering that it ran seven days ago. In writing, it's easier to remember where we left off if we write daily. We can get back into the groove much quicker and we don't risk burnout by trying to cram all our writing into one session.
Of course most of us writers are really marathoners: in it for the long haul; and can sit and write for hours on end, days on end, weeks on end. But you have to be consistent.
Which do you have the most trouble with, quality or quantity? (I'm a quantity-challenged writer because I like to write for hours on end and find it hard to chunk into smaller pieces of time. I'm not a huge self-editor in the early stages.)
Keep on keepin' on...