Some will use an medium sheen, such as Eg-Shel or Satin finishes. These will offer improved washability as compared to a flat finish while not developing as high a sheen as semi-gloss products. Another option, if you prefer a more muted sheen, is Low-Sheen/Matte finish. A more muted sheen such as these will still offer stain resistance and average washability.
Touching up an existing painted surface can be challenging - professional painters wrestle with this constantly. Ideally, use paint from the same can that was used originally, but reduce it about 10% to 15% with the reducer recommended on the can.If you are touching up walls on which the paint was applied with a roller, use a small trim roller. If the paint was brushed on, use a brush.Apply a small amount of the touch-up paint and "feather" the edges, starting at the outside edge of the touch-up area into the center of the area. "Feathering" entails drawing the brush across the area outside of the touch-up onto the new paint to create a transition that diminishes the appearance of the touch-up. If the surface had to be patched, use a primer sealer. Try to prime and paint to a natural break. Please note, though, that sometimes repaired areas may be noticeable. In this event, painting the entire wall may be the best option.
Most products are ready to go right out of the can with no reduction necessary. Some products can be reduced to some degree. The product's data page will indicate the maximum reduction allowed if any and the correct type of reducer. Please note that reducing a paint product past the recommended levels would produce a solution that may not offer the same performance characteristics as those indicated on the product's data page. Always use the recommended solvent and never reduce past the amounts recommended by the product's manufacturer.
Answer From a purely time savings consideration, airless spray is the most efficient way of delivering a paint product to a substrate. Also, when painting areas that have deep crevices, as in the case of 16/20 finish stucco (16/20 is very coarse), this method can get the product into otherwise hard to reach areas. However, when coating wood surfaces that have a significant variation in porosity and/or when coating cementitious surfaces with a thicker paint coating, back brushing or rolling can be recommended so that the material can be driven deeper into the substrate and so that the overall coat can be uniform.
This is often called a feature or accent wall. While this could depend on the overall space, the wall that comes into view opposite the main entrance is in most cases selected as the feature wall and should be the one to receive the special treatment.