The only night-sighted gun I've got is a S&W 1066 I got used. As a result, I suspect that the sights are somewhat dimmer than originally supplied due to age. I'm not sure, I haven't compared them side by side with another, younger set.
That being said, if it's dark enough to see the night sights, it's MUCH too dark to identify the target. But I can see the "Landing lights" on this gun across the room in the dark, which is probably a good thing if you need to find it in a hurry with bleary eyes. So long as you take the time to make sure of your target before you shoot it....