Check it out! Here is the link: hand expression vs. pumping video
Since I'm returning to my full time job soon, I decided to do a controlled comparison of hand expression vs. pumping to see which one goes quicker for me. I recorded this experiment.To summarize the results: I expressed about 20% more milk with my hand than with the pump. I was able to hand express milk when the pump was running dry. The hand expressed milk was less watery.
Note that I haven't used my pump in months but I have hand expressed occasionally when I needed milk. The results apply to my breasts, other breasts might be different.