The crashes are good for getting a retainer in a ward that is full and not accepting any more retainers. I really don't know why SE implemented the save retainer thing on maintenances when wards are limited in size. I currently have a placeholder retainer in the battle ward just because I'll need it in a few days yet it currently stocks no battle things. Why? Because if I didn't put it there the ward will be full when I do need it.