Kemper's nails grow unbelievably fast. I could probably cut them once a week and that wouldn't be enough. (Which is not to say that they get cut once a week....) And he plays dirty all the time. We haven't managed to get him to be able to wash his hands well enough to get that dirt out, so he basically has permanent black stripes at the tip of his fingers.
Rowan, on the other hand, hasn't needed his nails trimmed since he was an infant. He just takes care of it on his own. It's not that he's a nail biter or anything, and I don't actually see him picking at them all that often. I know he does it, but I don't know when. But honestly, I don't clip his nails. The exception is when he gets a hangnail and begs me to fix it. This usually serves as a bedtime stall tactic, and almost always involves toes rather than fingers.
On another note, I've noticed a recent change in Rowan at bedtime. To date, or goodnight ritual ends with a hug, kiss, and what we call a bip. The bip is a gentle pinch of the nose with your thumb and index finger. Morgan started it, I think, and "bip" was the sound he made the first time he did it. Anyway, each boy gets "a hug and a kiss and a bip" before we leave them for the night. (This is usually what finally gets me to cut Kemper's nails - when he gives one of us a bip that leaves a scratch on our nose.) Well, the last few nights, when I've asked Rowan if he wanted his hug, etc., he said he didn't. The first time he said no, I was certain that I would barely make it down the stairs before he called me back up because he'd changed his mind. Imagine my surprise when there wasn't a peep. Same story the next two nights. I guess he's growing up. And I guess I'm supposed to be sad about that. The jury's still out.