I cut mine and the kids diagonally. If it’s a egg and bacon sandwich I will get the egg (sunnyside up) from the pan and make the yolk run before flipping it upside down on top of the bacon (already on the bread), which helps spread the yolk around.
If I didn’t break the yolk then I run the risk of cutting through the yolk (when i cut diagonally) and having the yolk run onto the plate.
Also. When having bacon and eggs on a plate, and/or with toast, while it looks better to serve the bacon so you can see it, it’s better (for eating) to have the bacon underneath the other ingredients whether it be toast, egg, sausage (or all of the above), that way you don’t smoosh everything when you try and cut through the bacon (if it’s on top), and it’s the first thing you taste when you put your fork into your mouth.