I am wiring a 20amp circuit. The #12 seems pretty hard to
deal inside the electral box for the with the receptacle.

I notice all the books demonstrates that incoming wires
and outgoing ones connect to the seperate screws on the
receptacle. Is there any reason not to use a pigtail
and connect to the receptacle first, then connect it
together in/out wires with a wire nut, just like what
is done to a ground wires? That would be much easier
than to bend those short and hard #12 wires and try to
screw on those 4 hot/neutral wires?

I am talking about the middle of the run, non-split
receptacle.

Thanks.

Y.