If you stroke with your hand over the hull and it feels smooth it is okay. Scratches along the hull are less worse than others. Scratches are more worse in the forward part than in the aft part of the boat.
Foils should be fairly smooth. 800 or 1000 sanding paper required.
I do this ones per year. Wax is a must on gelcoat boats. Canuba is the best, forget all the other stuff, it is the same just more expensive.
Cheers,
Klaus