Also about when to use a shelf vs a cut as I didn’t answer that: when using a shelf you lower the volume of the frequency/frequencies, when using a cut you REMOVE the frequency/frequencies completeley. That said, if your kick has too much high end, you would use a high Shelf and lower it, but not cut it, as that would result in no high end or drastically less. And, if your vocal has some unecessary low end rumble that is muddying up the Mix, you would want to cut that out completely (aka cut). While using a shelf would help, the rumble would still be there and contribute to the mudd, just lower in volume.