Fred, that guy is definitely an artist! I haven't seen anyone else work shading into the definition of panel lines the way that he does.
Now, I'm going to put on my styrofoam helmet in case folks start throwing things at me for what I'm about to say.
The way that guy brings in the shading is impressive, but there is a drawback to this, in my not-so-worthy opinion. Shading totally depends on the viewers relationship to an object and light sources. This works great in a drawing or painting because the relationship of the light source, object and viewer never change. But, on an RC plane, those do change and do so constantly. I'm not even talking about while in flight, either. The viewer will either walk around the plane while observing it sitting on a table, pick it up and turn it in all directions. The shading applied to the plane won't change as it should while the plane is being manipulated. This causes the viewers brain to get confuzzled and the hard work that goes into the shading is lost on that viewer. If the builder is going to go to that much effort for the sake of a realistic appearance, it would be better to use the natural contours and shapes of the plane's surface to achieve shading. In his case, he is scratchbuilding, so why not sculpt the proper surface "topography" to achieve proper shading?
Now, I'm putting on my carbon fiber underwear and jump suit for what I'm about to say, next.
In my, again, not-so-worthy opinion, the definition of panel lines is WAY overdone on so many models that I've seen. In the case of ARF foamies, the molded panels lines are too wide and too deep, simply due to the limitations of molding foam. Many of the panel line definitions that I've seen darken the entire molded panel line, causing it to be way out of scale and way to predominant.
Additionally, replicating the appearance of panel lines is more complex than simply highlighting the line with black or other dark color.
Take a look at the picture of the B-25 attached. Looking at the top surface of the bomber, the difference that stands out to the eye is the values of the different panels, not the gap between them. The top surface is the most exposed in terms of light, so the panel lines are drowned out. In the less exposed areas, say below the waist gun, the panel lines are not evident. However, the rivets are and show up brighter than the panels. Again, different values are evident within the panels.
Next, take a look at the A-20. The panel lines are very evident, but actually show up as lighter values. Again, varying values are evident from panel to panel and within any given panel.
This is just my 0.02. BTW-I still think the mods I've seen look good!