Entrance hole protective covers? Yes? No?

Hi GBH, I usually have metal plates on mine but for me it’s about getting the size of the hole right and not the security angle.  Some years back my son had woodpeckers go through the side of his box and had all his chicks, so metal plate would not have stopped that.  However, most people feel a box is safer with them on, don’t know if how the birds feel about them though     This year, I had two camera boxes up one with a metal plate and the other without.  The one with a metal plate has had no interest that I know of, whereas the one with no metal plate had loads of interest but didn’t lead to a nest 
Sue