i'm going to be the oddball and say that shaders are more important.  i generally setup my lights in about 1 or 2 tests.  i tweak my shaders in from 15 to 30 tests.   if you have the right shader, your lights should be simple unless you've got a model that absolutely demands multiple light sources.  otherwise, really, there's only a few technical issues to deal with:

• use IBL to accurately reflect the ambient lighting of your scene
• add an inverse square falloff shader to your spotlight
• decide how to handle shadows.  raytraced shadows get grainy if you have a low spot angle and can use up a lot of processor power.  depth mapped shadows don't blur and fade like real ones, and can use a lot of processor power to get detail.

and that's pretty much it.

i haven't changed my default lighting setup much in ages.  i almost always use an IBL and two spots, but i change location, direction and intensity.   outdoors would be an IBL and one infinite light.  other than beginning to use raytraced lights, i haven't added any knowledge to my use of lights in about a year.  in terms of my materials, i've experimented and grown a lot, imho.  lately i've been working from bagginsbill's materials, and i'm pretty impressed.

just my 2 cents...