I guess the most important time for using DR is when you are navving in 3km visibility, which is of course legal.
If you can't see to navigate, you can't see other traffic well enough to have a high probability of spotting and avoiding it. Time to sit on the ground or file IFR and go get dirty.
Forget trying to squeeze through when vis is at the low end of the VFR spectrum.
Simply because it's legal doesn't really make it smart.