To simply try and match the hue that you see in the landscape (from either your photo or painting on location) can produce a monotonous painting. And I find that matching an accurate color temperature rather than a particular hue can capture the look and mood of the landscape more accurately, especially when working from a photograph.
Below are my demos from my oil and pastel classes. After I finished up my oil demo (study 1), I later decided to make an exercise of it for myself and continue to play around with color temperature, and try a slightly cooler palette overall (study 2). I have to say I think the first one captured the warm light a little better with the emphasis on the warms. But I suppose I just had to try the difference for myself to see that. (If I wasn't out of small panels, I would have painted a second version instead of on top of the first one!)
|green foliage study 1 - oil|
|green foliage study 2 - oil|
|green foliage study 3 - pastel|
|reference photo for oil study|
|reference photo for pastel study|