I've found my coturnix boys will crow all night regardless of lack of light once the testosterone kicks in. When they get obnoxious enough the extras go to freezer camp. Ahhh, peace and quite!
The roos that are left are set up with 4-7 hens of their own and each covey is housed separately. It's like magic when the young roosters know they have their own harem of hens how quiet they are. Of course you will keep roosters that are well marked, and the best behaved roosters for your quail hens. Any roo that beats up, rolls or otherwise abuses his hens goes into the freezer, they are easy to replace with a nicer roo. I also select for roosters with deep voices. If I have to hear him crow once in a while for the months or years I have him I don't want a shrill voiced roo crowing in my ear while I service their cages!