If I can extend it a bit: sometimes when you start a new job, the board state you inherit is actually subtly invalid (i.e. it will lead to an unsolvable solution), and you have to figure out the smallest number of numbers to "erase" to end up with a valid board state.

You get to realistically use the eraser maybe once per year, because nobody likes erasers. So you just compensate for it with lots of notes!