Pat,
The advantage of the one tee-marker is that it allows for use of areas not otherwise usable by fitting the square peg of the teeing ground into the round hole of the teeing area, so to speak. Even square tees have null space near the backs and corners that rarely can effectively be used. With one marker, placing the marker on light days of play in the corners and edges pushes play to these areas, allowing the middles to be utilized for busier days.
Now, for some math: the defined area of a two tee-marker setup is obviously two club-lengths behind a line drawn between the tee markers. Assuming an average tee marker width of 20 feet (7 paces, much wider and things begin to look very strange/it becomes very difficult to discern the front of the teeing ground) and an average driver length of 45 inches we have a defined teeing ground of 168 square feet. You, as most people surely notice, also understand that it is rare that wear and tear is spread evenly throughout the tee box. In fact, most of the divots are within one club-length of the front of the teeing ground and that is generous, so a two tee-marker setup effectively have 80 square feet of space used.
One tee marker, and two club lengths of radius, gives us an area of just under 200 square feet, most of which is more likely to be used. Even assuming most people will tee off in the area in front of the marker, we still have more usable space for the teeing ground.
So no, the practical application of math does not support your claim.
As for the edges, my statement still stands. Tee boxes lines have no bearing on how a golfer aims. Golfers are responsible for how they align themselves.
The best tee boxes follow the aboriginal contour or are blending in such that no edge or line jumps out at the golfer. If the golf course is reliant on tee box alignment, there are likely bigger architectural issues.