If he put it in correctly, the screws would have collided with their counterparts on the other side. Screwing in the second bracket you can hear some of the screws grinding against each other. This is the definition of overengineered.
Los clavos pueden rajar la madera prefiero hacerlo solo con tornillos. Las escuadras no siempre forman angulo recto, yo coloco una empaquetadura entre la escuadra y la madera.
