Landscape guy here. I'm often straining to get as much depth of field as I can get as I want both foreground and more-distant background sharp. Even so, I tend to avoid any aperture beyond about 7.1 unless I'm shooting for a sunstar effect. I do that because an effect called 'diffraction" softens the entire image as the physical size of the opening gets tiny, essentially becoming a pinhole camera 'lens'. It gets complicated, as there's an interplay between that opening and sensor size, but you can 'cheat'. I use Jon Sachs' free app DOF (also in iOS) to show me where I start getting into trouble. Download the (also free) readme for a complete explanation.