I work in Flash so Layiers are a bit odd. lol
for comics, I have 4 layers.
- Text/bubbles
- Gutters
- Panels
- Sketch
The panels are in symbols. When you click into them there are more Layers
- effects
- Character Art
- background
Background can be one layer or if there is a lot of stuff in the background it can get from 2 to 5 or more layers. lol
For just drawing art. I have the line art on three layers.
- Highlights/extra shading
- Shading.
- color
- outer line thickness/shadow.
- sketch
Thats just for a character art. If a background is involved, backgrounds can be an extra 2 to 7 layers. lol