It can be without sanding the flooring, or we can include it too. A good practice is to make the walls first, then the stairs (if any), and then the flooring (if included). The service has outstanding effect when renovating entire premises in houses, hotels, chalets, villas and other buildings.
Typically, when sanding the walls, it is necessary to remove all hanging things like paintings, lamps, elements and more. It can be done for an extra charge for the service, or you can do it by yourself.
It is highly advisable to make wall-sanding entirely so as not to leave places that are in the previous state or worst condition. Still, here we are talking about complete cycling. If you only want a partial sanding of a part, then that's ok.
Keep in mind this sanding service is once per 4-6 years, so you should consider what effect to achieve.
You may also consider that all nails should be removed (if any).