Regarding color temp issues, I recommend using a high-quality color temp meter for a little measuring
practice. After that, it's pretty easy to estimate the best filter. The practical difficulty will always be
when different parts of a scene are very differently illuminated. So you either have to make a creative
judgment as to which part to let drift, or find a compromise filter. As long as you're somewhere in the
ballpark, you're still going to have an exposure improvement over doing nothing. I've never tried warming grad filters which split the scene, but I suppose it's inevitable someone will if a scene is somehow evenly divided. Certainly not every problem can be solved using Ektar, but the same could be said for any other film, and you always have the option to carry more than one type. My own immediate
goal is simply to make true darkroom prints from Ektar etc which will set the standard for burning at the stake for incompetent witchcraft those who still does it the clumsy old crude way using inkjet!
I pity all these folks who judge images over the web and have yet to see a well done darkroom print.