[Imp]

Normally use default settings.
Similar to Right Deve will sometimes adjust for bad weather or night operations.
Not as major changes just spotting to 70-80% & very rarely hitting to 90%.
Low global visibility already seems to add its own penalties so not drastic changes just meant for extreme cases.

I have played around in WWII with increasing to hit as I feel first round accuracy from tanks is a bit lacking. Use default though as it effects all weapons.