this type of hold makes a challenging open-hand match.
The last type of the training hold [image 4. above] brings up a couple of general points about hold layout. In a home wall, you should create spaces that allow you to train in different ways. The last image shows a small section of slightly overhanging wall above a small angled roof. This a great place to work on hanging slopers, but thin edges are hard to use here because holds immediately underneath can obstruct access the thin edge or impinge on your forearm.
Placing the thin edge on the face of the sloper means that you can still access the thin edge even with a more bulky hold immediately below it. Plus, an array of these training holds let you practice similar movements from both sloping and thin open-hand edges.