2) I can easily be sucked into making profiles for many lighting situations (e.g., daylight early, noon, late; spring, summer, fall, winter, etc) Would that be total over-kill for landscapes, where I don't have to get "precise" color values, anyway? (I do understand that in very specific lighting situations where I want consistency among a group of pictures it would be good to profile that situation for those pictures.)
Besides the above-mentioned difference between continuous-spectrum light sources and spiked-spectrum ones, you may wish to create separate profile for deep twilight, when CT is high. White balance alone, as demonstrated here, is not enough:
Crescent-shaped pictogram shows the result of shooting in twilight, compared to daylight (background). Color temperature in this case was about 13500K.