Alvah,
The area we are mainly talking about is above and below the lock mortise. The width of these areas on the finished rifle you posted look to be about 5/16", maybe 3/8" wide. They would look better if they had been slimmed down to about 1/8" wide.
Yes, the nose and tail of the lock panel (fore and aft of the lock plate) will be wider than the top and bottom areas, because they look better when they are stretched out a bit. How much "stretch" in the nose and tail depends on the style or school of the gun. I like a little more stretch than the first picture, but it will give you an idea.
Rifle from 2011 by ALR member Curtis.
A rifle attributed to Andrew Fitchthorn.
Another by Curtis.
Gun by ALR member Flehto.