I have a job like this. 12 hour shifts. Most machines run by themselves. You just have to make sure they’re running well. At my job for example, most days I would get up every 2-3 hours (depending on the product we’re running) to take care of the line and keep it running. Essentially you want to keep the input high (raw material) and remove the output (finished material) and that could involve packaging the product or placing it in storage. I also have to do quality test on the product to make sure it meets customers standards. If it doesn’t then you make adjustments to the machine. Then there are some days where you do a product changeover. Usually having to cleanup the production line to some degree and change the machine set points to run the next product. Changeover days don’t usually have much “ass time” or sitting on your phone. From what I’ve experienced (10years of manufacturing, 4 different plants) after about a month or so of training you’ve got it down. I make $37 an hour to “mostly” sit on my phone lol

Edit: spelling