My experience:
I could tie them up by their feet and cut right under their chin with a VERY sharp knife quickly.
Later learned I could lay them on their back and cut also and lay towel over them.
But I had a hundred and twenty five of red broilers and found I could not stomach cleaning them. ( Why so many, I was thinking two chicken meals a week for a year).
Plucking was difficult as it takes a very big pot of hot water to dip a ten pound bird in, which I never found. Used a wheel barrow with less success and lots of water and LOTS waiting for water to boil.
I put off doing the rest for two months, during which they ate a LOT of money but didn't get much bigger. At six a day took forever to do them all, by then they were laying eggs.
After finally finished, I learned from my friend. He also seems to have lots of free time to do other fun things BECAUSE this what he does:
He lays the dead bird on its back, splits and peels back the breast skin, filets out the breast meat, skins and cuts off the legs and the meaty wing bone, and calls it good.
No plucking, boiling water, cleaning guts, cleaning up a huge mess. Took him less than 3 minutes. He laid the pieces in a clean pan and right to the kitchen.
After having done a hundred up beautifully whole, I discovered they were too tough to roast and had to be cut up to be pressure cooked anyway. So in the end, I did not need the skin or the backs or necks.