One reason I use Diafine for developing my nighttime stuff is to reduce the contrast problem. Works too. So does stand development in dilute Rodinal. Got examples of each in my goat skull photos uploaded here.
Dunno the why's and wherefors of each, tho' - don't have a densitometer.
Don't get me wrong - I'm not raising a glass to ignorance. I'm just happy to acknowledge what works for me.