Pre-industry describes early modernity, the period where press gangs roamed the streets to capture people and force them to crew a ship, and slaves were taken from their homelands and their ancestry decontextualized, rendering a return impossible.
While you could certainly make the case that the hours were fewer(because it was still agrarian) the state of labor relations suggests a huge demand for cheap workers, not efficient workers. Productivity needs inputs: with no canals or railroads, you couldn't get resources to factories in quantity, so you couldn't get the gains of automation. So the idle hours reflect a general impoverishment of possibility: nothing better to do with the idle bodies. Making them cheap, rather than good, reflects the drive to accumulate within the zero-sum dynamic of merchantalism. Or rather, you wanted to define good as "loyal to me and skilled at attending to my needs", which is different from "good at the job". So there was a lot of emphasis on preserving the body but minimizing resistance.
The labor exploitation in early industrialization reflects the combination of productivity dynamic and merchantalistic norms: now, in a competitive marketplace where you have a lot of opportunities to make products and quickly build wealth, there is a reason to overwork bodies and then dispose of them. That's never gone away, we've just engaged in some collective pushback from time to time, as Marx outlined.
But it could be that we're on the verge of another shift in the norms of labor relations. I suspect that's what is going on now. There are a lot of "pieces of the puzzle" that are ready to nibble away at existing norms.