depends on the shape, stiletto nails require a slightly thicker apex (maybe 3 credit cards thick) others like reasonable length square and round nails require only 2 credit cards thickness at the apex.
What I think your looking are just badly done nails, if you can see the apex from across the room , that is not good
If you look the curvature of a nice set of natural nails you will notice they normally follow the shape of a good set of acrylic or gel enhancements. It's not about building a mountain in the centre, its about having the bulk of the product in the centre for strength and tapered out at the edges while still looking like a natural nail.