Why would you be accepting deliveries "out of hours"? Presuming it is a controlled site you have the gate open to admit and exit the delivery vehicle (and probably during off-load). If it is an open site others could be present.

Even shunting deliveries from the stock yard to the factory you can end up with too many "what if's" when there is a single employee on site.

Factor in man-down systems or timed check-ins and it is more practical to have a second person present.

In a factory environment there are very few tasks without inherent risk meaning lone working is never advisable.

Out of hours (inc. shifts) the only time we have a lone worker is over the holiday period in the security lodge.

Shifts typically see two to three persons depending on requirements and never a lone operative.

I agree - I would be very wary of any loading / unloading operation with nobody available to assist if it goes badly wrong, which it so easily can.

There is a common practice of including on orders for deliveries a statement about the hours during which deliveries can be received and that they can not be taken outside these times except by special arrangement.