There is a balance to be achieved. Quantity is very good, and quality is very good. If you are deeply into a subject, then go all out with it. I've hit five thousand words on a hub before, and with dozens of pictures and videos.
There are many cases, however, when you can create a quality hub with three or six hundred words, a video; and a picture. The end question will always be whether or not YOU think you'd done a good job. If you are happy with your work, then nobody anywhere can tell you that you've not done a good job, or if they do, then it shouldn't matter to you if you think you've done a good job.