How thick can a 150W laser cut
If the fiber lasers have enough power, they can cut through reflective substances. They can cut any kind of metal, provided they have enough power. They will be limited in the thickness that they can cut.
With lasers, as long as you have your cutting parameters set right, you don’t really have to watch them. Laser cutters will do their things like automated robots. Occasionally though, they could go wrong. So, it’s recommended you watch them here and there. Plus, watching laser cutters cut is super awesome anyways.