Lightmap and texture baked into one image

Hey! I'm new into working with lightmaps and textures. I'm working on a mobile game and want good performance. I use Blender for baking the lightmaps (as I have Unity Free). I realized that you could bake it all together, textures, AO, and shadows into a single image and then use it as a normal texture on the mesh (with a simple diffuse shader for example). Is this an alternativ way to go? What pros comes with doing a seperate image just for the lightmap? Best regards Marcus