At home (intersection of three freeways in Brisbane), it takes only 45 seconds for my DSLR pointed high in the sky to get a middle histogram peak using f/4 and ISO 800.
The best skies I've ever experienced were in Roma QLD, where the same exposure settings didn't reach middle histogram even after 20 mins... a "modest" difference
Furthermore, since the signal is so much stronger and there's no light pollution gradient to deal with, processing is MUCH easier.