The nut slots from the factory are pretty shallow. They don't know what strings you're going to install or how high you want them, so they leave room in both dimensions for finessing them to where you need them to be. I think as they come, they're wide enough for a set of 10s, but any wider or lower you have to adjust for. Note: they always need to be lower. Nobody in their right mind would try to cut slots to their proper depth without stringing the thing up. That's just asking to throw away what could have been a perfectly good nut.