In the same sentence you asked "can you change" as well as "is it better to". Let me take that apart.

You can do either. It is the same process as any other material, even though it is a light shader. From the material room, you can save the node setups and reload them later. You can save from one light and load on another light.

However, be aware that the nodes don't tell the whole story. The light itself has properties, such as color and intensity, that appear to be in the nodes, but they don't actually get defined by the nodes. Poser treats these light parameters like they are independent quantities, regardless of what light shader you load. Supppose you save a light shader and at that time the light intensity is 50%. Days later you have a light at 100%, and you try loading that shader again. You will still be at 100%, not the 50% you saved it as.

So, if you want to record all the information, it is "better" to save the entire light as a light object in your library.

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Renderosity forum reply notifications are wonky. If I read a follow-up in a thread, but I don't myself reply, then notifications no longer happen AT ALL on that thread. So if I seem to be ignoring a question, that's why. (Updated September 23, 2019)