For me, I tend to write in the morning before work and that often gives me an hour at most to get down a scene and include as many words as I can. Many days that is just not enough time. I have to settle for getting the basics down. I tend to see a scene visually and try to think it through entirely before writing the words, but that also means that sometimes more detail springs into my mind the next morning. In other words, inspiration strikes again and I get a flood of additional ideas which I then go back and layer into the writing I've already done.
The first time I work on a chapter, I tend to "see" the dialogue and the physical action needed to move the plot forward at that point. Because of the time constraints and my focus on that, there are often parts of the scene that go unexplored.
Because, remember, that every scene--every chapter--needs to work on many levels to move the story forward. That's what I think of as the layers. There's a layer in the writing for each scene that involves the plot, the main conflict, or there should be. An additional layer is devoted to character interaction--bring characters closer together or driving them further apart. A third layer is there to improve and enlarge the world building and give depth to the setting. And a fourth layer involves the character arc and making sure each scene touches on the inner conflict of the characters. A fifth layer can involve being aware of conflict and that tension is going where it's needed.
Usually I get the first and second layer and parts of the third or fourth in an initial writing session of a scene. Then I spend some time rethinking that scene and seeing what additional ideas arrive in my brain to make the scene more complete and more detailed. The conflict needs to build and grow until the end of the scene is reached, or for shorter-termed tension, it is resolved in the scene.
This is even more true with action scenes which are so very visual. They tend to come out on paper as just a lot of movement--this character does this and this other character then has to react like that, repeated over and over. At my next sitting, I go back and add more descriptions that makes the writing less like a synopsis and more like a story. I work in the emotions from the character--the fear and the determination--to give the scene life. I allow brief thoughts from the POV character to break up the action just a touch and put space between the movements. That gives the reader a tiny break in the hopefully building excitement.
Take a look at your favorite writer's action scenes. I think you'll see how they work in quick descriptions, bursts of emotions and even moments of furious thinking/planning which all makes the scene richer like the layers of a cake.
To give you an idea, down below is the action scene I started on Saturday, with the additions from Sunday in blue. It's still a draft and I'll undoubtedly make more changes but it gives an idea of layering your writing.
Ramiro froze in the hallway while their plan of stealth crumbled around them. Teresa managed to dodge under the naked woman’s wild swing with the Diviner by falling to the floor and scrambling back. Ramiro hesitated as his other companions, the two priests, receded to a safe distance. Self-preservation screamed at him to flee, weaponless and therefore helpless, but the urge to protect the innocent proved stronger. Ramiro jumped in to intercept the next attack on Teresa, sweeping the tray around as polishing cloths flew everywhere. The solid staff of the Diviner hit the back of the wooden tray with an audible whack. Ramiro cringed expecting the tray to split. Instead, the Diviner burst in a spray of splinters, the slim rod flying apart.
Ramiro’s eyes closed as splinters cut into his face. Someone screamed. He overbalanced when the resistance against the tray vanished and landed hard on his left elbow on the relentless marble floor. Telo shot forward, leaving Father Amor by the coal hole, and grabbed the naked woman around the neck, pulling her down. Her stiffened fist made contact with his middle, sending the air rushing out of Telo’s lungs in an explosive cough.
A man burst out of the sleeping room, adjusting his white robe around his hips and brandishing another Diviner. Ramiro managed to stick out his leg. The Northerner’s feet caught on it, and he stumbled across the hall to bang into the wall. As Ramiro struggled to his feet, Teresa jumped on the man’s back. They bumbled across the hallway with the Diviner flailing; the Northerner unable to quite bend his arm to reach Teresa for the kill.
Ramiro swung the tray in an upstroke to push the Diviner away. The barest brush with the tray and the white staff cracked apart like the first, showering them with bone-like shards.
Doors opened all along the hall. Ramiro’s heart sank as more Northern priests poured out.
“Hold him still,” Ramiro shouted to Teresa to little avail. But years of training with grown men while he still wore his mother’s apron strings had taught him many things: how to fight or defend, how to survive, and how to be lethal in an instant. He punched out with his sore left arm and landed his fist squarely in the Northerner’s throat, hearing fragile bones and cartilage break. The man folded, hands grasping his neck as he choked, taking Teresa down with him.
I do my layering in a chapter before moving on to the next scene, but I'm guessing many people do their layering after the first draft is done and as they go back and edit. Do you use the technique of layering or something else?