It's done different ways.
let's look again at this:
These are examples of laps that come to the same point, this construction is called the Heidenkreuz, because it looks something like a cross, and because it's a practice (a framed gable) brought by the pagan Alemanni to the Christian Berner Oberland about the 7th century or so.
This in my opinion is the weakness of the lap dovetail.
The best solution in my opinion is to push the angle of the braces well past 45 degrees, typically they will be either 3:4 or 2:3 (I prefer 3:4, I think it looks nicer) This gives you more space to work with within the same width of timber. Generally the two will meet in the middle and form a point.
These examples both show a small bit of wood between them.
When building a frame, I like a different approach, it's an old one that has an interesting look to it. This is to make all of the braces come in to the timber at a different height, which lets me give each one as much space along the face of the timber it needs. I'm working on the drawings for my barn this week, I'll put up a picture of one of the posts with 3 braces at different heights when I get that drawing made
