However, for silkies I did have a breeder tell me once that she uses 1:5.
Some roos are just going to overbreed the hens and some are just gentlemen and the ladies keep their feathers and don't look all torn up. So the ideal is where they ladies don't get to the overbred point.
Some keep a breeding trio of one roo to two hens. I haven't done this type of thing except for quarantine.