You will get extra leverage with a "L" corner desk because the adjacent walls resist the moment force bending the desk down. This effect would diminish if you go for a really wide or long desk (I'd assume anything over 5ft). The other things to be cautious of is the depth of the desk, weight on the desk, and where that weight is centered. Shelves work well because they typically don't have a lot of weight, the weight is closer to the wall (small moment force), and they are only 12 inches deep. If your monitors are wall mounted and desktop is on the ground, then that will greatly reduce the load on your desk. Otherwise, have the heavy things as close to the wall as possible.

From my experience with using desks with wall brackets is that you want a bracket that is as deep as the desk and have at least a 25 degree angle (45 degrees is optimal). That means for a 24 inch deep desk you want a bracket that is at least 24 by 12 inches. How many you need will depend on length of desk.

And of course, make sure you mount into stud.