I do understand that there are a variety of ways to attempt WB adjustment and I certainly don’t have enough knowledge or experience to offer any advice on what might be better.
My question was focused on understanding the Color Temperature (CT) Tool that turned up in GIMP 2.10. It may be that my understanding about some basic characteristics of WB is flawed. One basic idea that I have in mind is that the process of developing an image from the raw sensor data requires dealing with WB considerations. I also have the idea that CT ends up being a property that can be associated with this development process for all photographs. In that, no matter what method the user or camera uses to adjust WB the software ends up associating a CT with the process of developing raw data into an image. Is that a valid concept? If not then I need to get a better understanding of how WB works.
If so, then I’m thinking, there is a CT associated with the initial development of raw data into an image. Then that CT can be seen as a property of the image. Because GIMP does NOT develop raw data this is always done elsewhere. I’m thinking that this is why GIMP (correctly?) chooses not to refer to White Balance. My impression is that GIMP’s CT Tool wants to know what it is. Absent a standard method of tracking this property it is understandable that GIMP needs for the user to supply it and my question is simply how does GIMP think it is supposed to be obtained.
Another concept that I have is that once we start processing that initial image (i.e., file that has already been developed) with editing software an extensive set of tools come into play that pretty much all adjust the color in some way or another. Once we start doing that, I’m inclined to think that CT becomes less relevant and that it doesn’t take much to make it meaningless. Might this explain why there is no attempt to track WB (or CT) automatically such as by using an element of metadata? Might this be why experienced photographers don’t really expect there to be a way to find that initial value of CT? Maybe the CT tool in GIMP should be avoided except is those, possibly, rare cases where, as Elle says, it happens to produce a nice/pleasing affect.