I use all my colour-balancing and -converting filers all the time. In the right situation they greatly improve tonality to approximate what our eye-brain combo, which does not merely focus selectively, but also adjusts to brightness and colour-casts instantaneously, thinks it sees. 80A in incandescent, FL-day in fluorescent, 81A/B for haze or shade/overcast, all are just as essential for good people-pictures as they were with film, giving decent skin-tones, and also with digital avoiding nasty underexposure through the meter’s ‘seeing’ light that is not useful and exposing accordingly. The only time I do not use any is when I want, say, the strong blue shadows of a purely landscape shot made on a bright day to be recorded ‘accurately’. Nearly always I have the WB in my Pentax cams set on Daylight/Sunlight, and the result is so good that only the most minor tweaking may be needed in post, say to make white paper or paintwork look pure white.
One situation in which such filters really come into their own is mixed lighting. I have been in big church interiors where there was daylight coming through the stained glass, and some combination of artificial light on the interior stonework. Or modern interiors with fluorescent overhead and daylight coming in at the windows. I start preferably with a graycard reading. No in-post tweaks will ever give me a really good result, and that includes so-called ‘filters’ which just put a layer of colour indiscriminately over the whole image.
I wish that when I was new at digital work I’d known all this: for these shots, for instance, of the interior of that great church, King’s College Chapel, Cambridge:
Priscilla Turner's Store : IWASTHERE11A (Page 1) and most of these:
Priscilla Turner's Store : IWASTHERE11B (Page 1) , the stonework, which I ‘saw’ as a light beige, and everything else, showed up loud and clear with a strong orange. No amount of post work could correct that fully without shifting the colours of the so-celebrated stained glass; which incidentally varied according to whether the light was coming in from the E, W, N or S on a bright afternoon.