As the door opened you could hear a droning, five...four...three...two... then the door shut before the final number was counted. The shop mail was hastily placed on the reception counter and the flustered-looking postman rushed out, without even a greeting to the staff in the shop. The urgency was to get back to the delivery van, press the off switch before the count of 'one' was complete.
The post delivery round is in a remote rural area, covering various villages and their businesses, the businesses get priority for the morning delivery over domestic post. No doubt, the postman had to get to the other villages and businesses on the route, each time, being counted out of his van with the individual deliveries and then being counted back. No two places have their counters or mail boxes in the same place.
Five seconds is a hellish and unrealistic time scale to work to per mail drop. What if it is not possible to park the van, (leaving the engine running for quick departure, which is illegal) close to where the mail needs to go. The postman is forced to double park as close as he can get. Other road users be damned! What if the conditions underfoot are slippery? We tend to have very inclement conditions; it can be icy in Winter; if there is a gale blowing, a regular feature of our climate, that can be another obstacle to timed speed deliveries. It is, in my view a recipe for an accident, it is also a recipe for developing, amongst other things, health problems.