@murphy "Open & notorious" is important as to the landowners actions of occupation and use in case there is a dispute and AP is an applicable doctrine in that dispute (title issue).
That the landowners be made aware of the monument's location when or shortly after it is set is important, but what they do with that knowledge afterward is up to them.?ÿ In urban and suburban locations, I prefer to bury them.?ÿ In locations that the surface soils are likely to get disturbed, I bury them well below the likely disturbance (i.e. agricultural, gardens, etc.).?ÿ In rural areas, I will typically set them flush.?ÿ I like the idea of a piece of PVC as a witness stake (informing the landowner that the actual corner is marked by the IP/Cap at or a bit below ground surface).?ÿ?ÿ
In the area I've recently relocated to, I've also seen use of metal T-bar fence posts, painted bright red & white similarly set as witness stakes/guard posts in rural, woody or brushy locations.?ÿ I like that and will likely be doing the same from now on.