In one particular cabinet, we've had trouble with shelf brackets popping out and shearing out the peg holes for the other three brackets. This design spreads the load over three peg holes, but more importantly keeps the bracket from coming out unless the shelf is removed.

Print in orientation shown, without supports turned on. Integrally designed supports pop right out after printing on my Aurora A3.

For cabinet shelves drilled 3/16 inches in diameter on 1 1/4 inch centers.