What kinds of circuits need precise resistors?

Timing circuits, and any circuit that depends on the resistor value being fairly precise, such as voltage dividers and comparators. Old story....engineers knew that you couldn't pick through a bunch of loose precision resistors to find close tolerance resistors....The manufacurer already took the close precision resistors and sold them separately. This is not so true these days. Even low tolerance resistors might be high precision. Usually the manufacturer will fill the loose precision needs with parts better than required.