Over 20 I use pre-compositing which is a trick from animation. So each panel is assembled on a page, while being a whole composition in itself. I have about 10 panels for the assemble page where I split fonts, frames, initial sketches, bubbles, drawings and more.
Within each panel on the drawing layer, there are layers for the second sets of sketches. I sketch the backgrounds separately from characters, props, and cars. Characters often have their own individual layers.
It is is a very methodical approach to comics that was inspired from my background in animation where everything is on a separate layer or sheet.
The drawing below is the initial sketch. The title logo is on its own layer. The frames are on their own layers. The sketch is also on a separate layer. The image below doesn't even include the clean drawings.
The image below is the detailed sketch or pencil of the top panel. As you can see, the characters are on separate layers. The trees in the foreground are on their own layers. The water has its own layer. The trees inn the background have their own layers. The boat and the deck are also on their own layers. These are just sketches.
Finally, there are the clean layers. Here the characters have their layers, the sky and the water are on a layer, but the starts and water reflections are on a separate layer. The trees in the background have a layer, those in the foreground do too. The deck and the waterfront are on separate decks. Finally the boat is floating apart!
The captions are added after too!
Oof, that's how Johnny Bullet comes to life every week.