I work for royal mail as a postman, Thought I would let you know how things work our end.
Any post for the day will arrive at the office about 5am. All post is then sorted and delivered without fail. nothing is ever left behind, if it is we either get a call to go back and get it or someone else takes it out and delivers it.
If say you are worried that you GTA is misplaced in the van and it turns up at the end of the walk or something like that, it will still be delivered (we would get in alot of trouble for taking it back to the office).
sometimes say a letter that we all know would go straight in the bin such as an advertisment for new sofa may get taken back, but nothing more then that, and besides things like that happening are very rare.
My brother works in the sorting office, he is there now, I will ask him when he is back to see if they had a big volume of 'ps3/xbox' shaped parcels today