For me it depends. (the handle)
For me a handle that is deeper top to bottom has to be thinner to not feel clumsy.
A handle that is narrower top to bottom I want to be wider relative to it's depth.
For when I am whittling thru something to avoid pain on the backward pressure I want it to be wide across the spine.
However in order to avoid feeling clumsy I want the scales to taper both toward the ricasso and also taper toward the part where your fingers curl around the handle.
I find that I can have a wide handle that has great finesse and control as long as the slabs taper top to bottom too.
For instance:
Of these 4 knives I find the far left is great for fine work but not as good for whittling thru something thick because the rear of the handle is both square and thinner.
The third from the left is fantastically comfortable for extended whittling thru thick wood but a bit clumsy for me on fine cutting due to the overall diameter.
The second and fourth from the left are the best overall because they have enough swell and rear width but taper.
The shape of the top knife here in this pic for me requires a thinner handle because it is deeper. The bottom knife a wider and more round handle.
Not sure if this pic shows it well but the slabs taper to not much wider than the actual tang on this knife so it has good control
Maybe you can see it a bit better on this one:
Or maybe this shows it better, wide across the back so it is flat on your palm but narrow for control where your fingers go round
So for me it sort of goes beyond thin versus thick scales and more dependant on the actual shape of the handle and knife and how they are contoured.:thumbup: