I'd agree, it's always better to get a good and color corrected negative, but if the source of the light is, say, a mix of flourescent, tungsten, natural light then will the FLD filter work? Or some other combination?
As mentioned before, probably a few tests would be in order!
Fluorescent lighting can be corrected - to a point ... not completely.
The spectra of ALL fluorescent lighting is "bumpy"; not really a smooth curve as would be the result of "black body radiation", and the dichroic correction in the enlarger will be smooth. Add to that the vagaries of the film emulsion in response to the bumpiness and the problem is even greater.
The images can be improved. I've found that it takes a lot of effort - something that would place the printing well into the "custom" area. A FLD filter - I've used them - will HELP, but IMHO will not be a panacea. If I have no other choice but to photograph under fluorescent lighting, I would most certainly use the FLD.
I would say that flourescent lighting may be partially accounted for by the film you are using. If you are shooting under flourescent, use Kodak which naturally has a golden overtone and cuts the stark cyan of flourescents. Do not use Konica or Fuji as they are blue and green dominate respectively.
FLD or 30m compensating filter, but you'll loose film speed because of the filter factor.
You might try using Fuji NPS (160) or NPH (400) with no filter. the Fuji film does an excellent job of compensating for fluorescent light with no filters.