>>536339195
Sketch layers are for visualizing construction. Tracing is when it's someone else's completed work.
>I always thought you work from your 'inner eye' with a blank canvas
They still started with the blank canvas. Certainly no illustrators just start rendering off the bat.
There are some hyper-specialists who did skip sketching, like the late Kim Jung Gi. Very rare that you don't fuss with the base idea to try and make it novel or appealing, though.