But what if the human only has to intervene once every 100 hours, that’s a huge productivity boost.

The point is you don't know when of those 100 hours that is, so you still need to monitor the full 100 hour time span.

Can still be a boost. But definitely not the same magnitude.

And one might also wonder still if we need a general language model to mow the grass or just a simpler solution towards to problem of driving a mower over a fixed property line automatically. Something you could probably solve with wwii era technology, honestly.