Technical in a Collet die (neck sizing only) you do not need lube, but it is not a bad idea just to be on the safe side that the case does not get stuck (big pain).
For regular full length resizing dies, yes you need lube.
Am very familiar with the full length resizing routine; just wanted to know if it wouldn't hurt to also make things a bit slicker with the old whack-a-mole. Will doubtless be going to a proper press-mounted collet die later, but for now the whack-a-mole does the job just fine.