I write with a pretty random schedule. Time of day is in the evening mostly, because that's usually the only time school affords me. In the summer I would write in the afternoon. Sometimes it's only 500 words which are written in a half hour on a good day, where I don't have time, or an hour and a half on a really bad day, when I have all the time in the world. Other times it's almost 6,000, and it takes me around five hours.
It depends on the scene I'm writing - if it's a climactic or otherwise earth-shattering scene, and I have the time, that's when 6,000 words in five hours happens. My third novel, being the conclusion, is filled to the brim with earth shattering scenes. That's how I was able to write it in six months even though it's the longest, when the first took me a year and the second nine months.