This project wasn't for a client it was just me trying to run Blender through it paces and doing a project a client may request. It took forever in general terms.

The modeling modifier stack seems to just get in the way, but do acknowledge that some aspects of it are nice. The mirroring/symmetry and arraying is somewhat of a joke. What I don't understand is when you go into the Sculpting symmetry is on by default and for normal modeling you have to set it all up. PITA!
There wasn't much of speed difference on my PC the GPU (GTX1050ti) and CPU (i7-8086K 4GHz) rendered this scene within a minute of each other - 7m19s GPU 8m12s CPU.
I just assumed the lights have falloffs built in. Otherwise they couldn't call it PBR rendering - right?
Sure they can call it PBR rendering, as long as you set lights up properly, the rendering will be Physicly based as long as you set the stuff up right, the fact that it´s not there by default is just a matter of poorly implemented workflow I would say..but to assume it is built in default, no I do not think so, it seems the sunlight intensity is constant...se below from 2.91 docs..
"Sun Light
A sun light provides light of
constant intensity emitted in a single direction from infinitely far away. It can be very handy for a uniform clear daylight open-space illumination. In the 3D Viewport, the sun light is represented by an encircled black dot with rays emitting from it, plus a dashed line indicating the direction of the light."
So My conclusion is that unlike Lightwaves distant light or sunlight, the sunlight in blender isn´t setup with any inverse quadratic fallof by default.
As for symmetry in blender, I don´t see any PIT, and I do not see symmetry on by default, maybe I changed that but I don´t think so, when sculpting symmetry isn´t on by default, and it´s just a little click on the x, y, z buttons to turn it on or off.
My blender 2.92.0 alpha..I didn´t save out a prefered default state, but yet..when I start a new scene based on sculpting, no symmetry is active by default as you say, neither if I start with a simple new object and go in to sculpt mode, but perhaps they recently changed that, will have to check 2.8.
Same with edit mode, just click on x button on off ..not much different there when in edit mode, and not different from lightwave, except lightwave only have One axis to set symmetry on, where blender have all three axis to your disposal.
Then you have the modifiers for symmetry, which takes more work, but it works in levels lightwave isn´t close to, and with other modifiers..none of that is possible in Lightwave.
If you compare symmetry between Lightwave and Blender, you should only do so in the same class level..such as direct editing, and not the modifiers.
As for GPU VS CPU, guess you have more power for the CPU than the GPU, that is for final rendering I suppose, but how does it compare in the viewport iteration, do you get any sense of faster viewport refreshment/refinement with GPU than CPU, I would suggest you try with hair rendering there, or volumetrics.