That's also a favoured way of finding out if anyone is in to see if it's worthwhile breaking in.

The converted house I live was burgled in Jan and I found out recently that another few converted houses in the road have been done since.

The burglars come along and buzz all the buzzers to see if anyone is in. If not, they shove in the door (they target houses with older simple snib locks) and then take their time inside the house to break down internal 'external' doors to the flats since they know there's no-one there to hear or see.