Not entirely true as far as full timers getting
beat for more hours. I remember many a times working 13-14 hours part timing it, 6 hours preload during october-january or february and 7-8 hours delivering after preload.
Also, more and more part timers are making it a career for everyones got their own reasons to stay part time.
And, preload in my opinion CAN be way more tough on the body than delivering can and at least during peak drivers get to use helpers!
Niether job is easy though i think thats been very very established.... Especially as time goes on it gets harder and harder with more and more work along the way....