Seams and jagged edges after mesh map bake

After importing and mesh map baking this FBX, the Ambient Occlusion mesh map has jagged edges on hard edges where there are no seams. The mesh is practically all rectangular boxes (a wooden shack made of planks). If I'm to eliminate all the jagged edges, should I be adding a seam to almost all of them? That seems excessive, as there'll be a lot more islands and the texel density will be lowered? The horizontal mesh across the door has no backface, so I haven't added seams to the long edge, only the corners.