sometimes it varies depending on the page (especially if it's animated because then fml all hell breaks loose there are no rules), but for grayscale pages it's usually 7-8 layers:
-text and speech bubbles
-panel boxes (i outline panels in grayscale comics, but avoid them in color comics)
-character lineart
-background lineart
-misc effects (e.g. overlay, multiply, gradient)
-flats shading
-flats
the layer count varies a lot more when i work in color, but it's usually 8-10 layers:
-text and speech bubbles
-gradient overlay
-overall shading
-character lineart
-background lineart
-character shading
-character flats
-background shading
-background details
-background flats
as you can imagine, my grayscale files are laughably small compared to my RGB ones LOL
there's also a sketch layer that prefaces everything, but it usually gets deleted once the text and lineart are done