Some people know this, other people don't, but I do not write the scene of my books in order. Sometimes the first scene written isn't even a key scene or a crisis point. Some times it's just an idea I have in my head for a scene, but doesn't yet have a story to go with it.
When I begin to seriously write a story, I start with a one word sentence. Then I do an outline of the crisis points. After that, I do a key scene outline. Finally I write a scene outline, where I start off trying to connect key scenes and crisis points with actual actions. All the way along, I am writing scenes. The number of scenes is in the hundreds. This is the key to being able to bounce around the story.
I've talked to several people who try to write in chronological order. I suppose the advantage is that is how stories are normally told to an audience. Also, you don't write something later on and find you don't have a way of connecting it to something you wrote previously.
However, people who want to write must accept the fact that they will change things, especially once the draft is out of the way. Scenes will be reordered, reworked, dropped, and added. That makes writing scenes in order very limiting.
Let me introduce something I'm currently working on: Legacy of Valor. For those who have read my first book and followed my contribution to the Work in Progress Character Blog Hop, you know the first book I've written in the Dreamscape Warrior Series was Price of Vengeance. Promise of Mercy is nearing the time when I will submit it to the publisher. Legacy of Valor can be considered Book 1.5. Liam finds himself commanding against a much bigger force. No spoilers but trying to figure out logistics, and how he will overcome three-to-one then six-to-one odds was a daunting prospect.
So most of the battle scenes haven't been written yet. The reason is simple. I had no idea how Liam and his troops were going to survive the first encounter, let alone the entire novel. I took writing the end, which I've just begun doing, to clarify the answer. Jumping ahead forced me to consider the ways in which a small force can defeat a larger one.
At the Battle of Thermopylae, the Greeks stood off and delayed a much large army of Persians by using terrain to funnel the Persians down so the 300 Spartans faced manageable numbers. Major General John Buford used a similar tactic at Gettysburg to stack up the Confederate while the rest of the Union Army arrived.
I finally have my answer and can start working on the preceding scenes. Writing scenes out of order allows the writer to explore different ideas at different points. It also helps in the development of a character. You may discover something that you can bring backwards. How do you know what scene to write next. I usually go with what feels right at the moment.