This will make a very small table of six cells. But if you move one of those layers a little bit away from the others and convert layers to tables, you'll find the number of table cells increase to 16. That's because new cells are needed for the gaps between layers. These controls are under the View menu. If you set up a grid before starting layout, then your layers can be snapped to the grid, assuring that you won't need extra table cells.
Snug layers up to each other.
Check the height and width of your layers in the Property Inspector. Even if two layers have their left edges aligned, if they're of different widths they can require an extra table row. If you're using a grid system then the height and width will usually be a multiple of your grid size. If you're not using a grid, consider using the Align Layers commands in the Modify menu to make sure that layers at a distance from each other actually share the same positions. If you collapse cells smaller than a dozen or so pixels, then this will reduce the number of rows and columns in the table.