I feel like Kadri is mostly right. The exception for me would be not in a full complete scene, but rather you could think like in the OP for a "good" starting scene... So not "final", but most of the way. So for example a bright sunny scene with little to no clouds. You could optimize the light and render for that, and then just drop in any terrain tgc clip. For the most part a bright sunny day is not going to give you too much trouble, I think. But add clouds and complex lighting (god rays, haze, mist, ect) and then all of the surfaces are going to play different. Not to mention optimizations for different clouds in different light.
About saving a TGC of an entire node network.. Yes, no problem (that I have ever seen, or at least remember), not a bad idea with respect to your OP, assuming you can fine tune things for what you want to do.
Probably you can not just have one "perfect" set up. But perhaps you could make several respecting a few main situations (overcast, sunset, sun rise, sunny day) and use those as your starting point for render farm quality.
Just keep notes when you work so you can alter the presets more quickly when fine tuning a specific scene for rendering.
I should take my own advice on this, but I like to suffer and never get anywhere