I think Barry's right. Certain things are simply not possible with the different techniques.
One advantage of brush painting, though, that I hardly ever see people mention, is that if you're thinning your paint on a palette, and even moreso if you're mixing your own shades, is that you can alter the hue as you're going by mixing more or less of different shades in, or just using slightly more and slightly less dilute paint to have higher or lower saturation of the colour you're working in.
I think I've got this right (but pls correct me if I'm off track): much of what is being attempted in pre-shading is, as far as I can tell, an attempt to avoid a perfectly even finish on the model as this just doesn't look realistic at scale. An even finish is what airbrushing is particularly good at - hence why the 1:1 scale originals are usually sprayed themselves! Working with a brush, the issue is often the reverse - trying for a more uniform finish (hence working with multiple thinned layers). If you don't try too hard at that, you can get some interesting textures on the final product. The big no-no is visible brush-strokes, though (so: again thinned paints, don't paint over still-tacky base coats etc).
Wish I had better photos of it, but here's a Hampden bomber I did, entirely brush-painted. Other aspects of the painting aren't so great (not happy with the masked edges of the canopies, and there's quite a 'step' between camo shades at points), but I'm pleased with the overall finish I achieved there. And it doesn't take an expert - this was my fifth model (as an adult!).