I'm with Rosebud. I'm a twitchy, picky, bitey person and chewed my nails to a bloody pulp throughout childhood. I have some sensory issues, but that term didn't exist when I was a kid. The need to pick at and worry any irregularity on my skin, clothing or nails is just part of it, an inherent part of me. My mom, my teachers, anybody who made an issue of it only made it worse.
In grade school, I would put bad-tasting things on my nails, even once buying a commercial anti-bite liquid with my own allowance. Never worked. I was finally able to stop the nail-biting (and hair twirling and chewing) my senior year in high school, but it took months of dedicated effort. I always switched to manipulating something smooth – a pebble or a string of beads, and filing off all roughness from my nails the moment they appeared. I also still will get a sheet of scratch paper and gouge and fray the edges for however long I have to sit still. Or styrofoam cups, another good target that's not my own body.
I still have to do this, and I'm 63. If I get any 'thing' that doesn't belong on my skin, nails or cuticles, I find myself tearing and nibbling at it. I stop and find something else to do as soon as I notice.
If your daughter has specific times that she does this, gently offer her something else to do with her hands. Reading or watching TV, sitting quietly for any reason, when she's going to bed and doing "nothing" are probably her worst times. There are also chewing sticks made especially for kids with oral sensory dysfunctions that give them a safe alternative for their need to chew. You can find these online. But if you bug her about it, you may only make her feel twitchier and more in need of this behavior.