Staying with my inlaws just now. They are very security conscious, have at least three locks on each of porch door, front door and back door. The back door also has a gauze screen door which opens outwards - so they can have the back door open during the day without getting flies in and that (he’s Australian). At night they hook an elastic band from the handle of the screen door to the handle of the back door. I guess this is to stop it flapping about but I’ve never seen it flap about ever, elastic band or no, so I’ve irked myself imagining that this actually is a pointlessly minimal extra level of security.
I’ve also just snapped said elastic band cos I forgot it was there going out for a cig just now, so had to tie it back together which was an extremely minorly irking thing to have to do.