> Instead, it brought 16 hour factory shifts.

To paraphrase Marx, "And so, the equivalent amount of labour required to produce the goods needed to sustain a worker for a day is, say, 4 hours. But that doesn't mean the selfsame worker can work for no longer that 4 hours! He can be forced to work six, or eight, or twelve hours a day, and whatever additional goods he produces — that's the surplus product, which in this case goes straight to line up the factory owner's pockets".