For information, here in France a carpentry tenon is 3cm (approx 1 3/16"). Regardless of the species of wood and the design of the frame. Generally they are centred but when a certain face alignment is sought they are often 3cm from the edge. A standard french carpentry tool is the jauge which is coincidentally 3cm large. Pegs are placed at 3cm from the edge of the timber containing the mortice.

...do you see a pattern here?