One of the things I have learned in being a writer is measure.
Everything must be done in a measured way when you are writing. Even when you are going great guns and your typewriter (or in this day and age your computer) is hot you have to be measured in the way you approach your work. I used to stay up all night and write until four or five in the morning. I no longer do that because A.) I’m older and I need my sleep, and B.) I’m more mature as a writer and I realize that more can be accomplished with small dedicated writing sessions than a marathon.
Which is not to say I have not done writing marathons recently. A couple of years ago I wrote three stories in three days and I documented it all on my old Live Journal blog. Part of the reason I did it was because I wanted a challenge and I wanted to prove to myself I could do it.
I suppose for me writing is always going to be about proving whether or not I can do something. The new Haxan novel I am working on is itself a real challenge. That’s what drew me to it in the first place. Everyone has different reasons for writing. Even I have very different reasons from day to day. The time I am talking about was when I wanted to prove to myself I could write three stories in three days. And I did it! Even better, I sold two of them and the third, “Alpenglow” was recently released by Argo Navis Publishing.
I mention this not to toot my own horn (although I am not against that, either) but because I have been thinking about that time, and the kind of writer I was then, and the kind of writer I am now. Today I am more careful in how I write. I think as a result my writing is better than it was. I have always been focused. That has never been a big problem for me. But the act of writing and marrying it with the mental adaptability and preparation that goes with it…well, I think I’ve gotten better at that.
Like they say, practice makes perfect. Or, if not perfect, at least nominally better. And for a writer that is good enough.
(On the topic of why I write, I want to come back to this and address it in further detail later on. It is personal, though.)
Hoover's Corner 
I agree with you completely here, K.M. Small regular high-quality writing sessions are definitely the way to go. Thanks so much for your ongoing unselfish guidance. Happy Valentine’s Day to you all there.
I’ve tried the long marathons and sometimes they are necessary. But you are right, I tend to do better work in shorter venues.