I have one of the 9v. battery ones. DeWalt, I believe. It's all but useless. 16" centers? Not my house. The load bearing external walls are 24" on center. The interior walls are all non load bearing, and they are just placed at random intervals. It's like the framing crew was drunk or maybe they couldn't afford a measuring tape or something. The only place I can count on finding a stud is at the corner and at doors. Everything else is just random.
And don't even get me started about the shelving in the closets. They were just finish nailed into the drywall. Nothing attached to the studs at all. Add a little weight, and kaboom! When the shelving in the master closet fell at 3am a few weeks after we moved in I thought some one had broken in. I was relieved to find that our clothes and whatzits were all over the floor instead. I had to redo all the shelving in all the closets and utility rooms to attach them to studs. None of them were originally.