Having great results from wet sanding often lies in the smallest of details.
The most important step of wet sanding paint is the first step; this is when all the texture gets sanded out and any other flaws. It is easy to let something go and get it in the next step.
Edges of panels might be the most crucial of these details. They need to be sanded completely flat, with no exception. Even a small spot that isn’t flat might appear to go away in the following sanding steps, but it always shows up; and will compromise the quality of the entire panel.
The two pictures below show the difference in edges being sanded. Completely flat is the only way to do it. The first picture shows that the edge is not sanded enough. The bottom picture is how every edge needs to be finished in the first step of sanding