Day vs night effectiveness is roughly equal for me, depending on the terrain and target. I prefer the day, but night is pretty neat sometimes.
I prefer to hunt alone at night. I know how to do it well and my kill ratio is very high. But when I hunt with others at night our kill ratio drops to around 50% and that ticks me off.
The biggest thing is in my area, predators usually shy away from two spotlights that are on at the same time. So both of us will be scanning and when one sees eyes, the other guy is supposed to shut his light off. But my hunting partners don't shut their lights off. I get it, it's natural to want to see the eyes. By the time they shut their light off it's too late, the critter has already been spooked by the two lights and they typically will not come closer. Operating the lights incorrectly in general hurts success, like shining the light on your partner, spill light, and not scanning quickly or effectively.
When I hunt alone at night, I have no problem getting predators to come close.