For me it's one pass through the 17AH neck die, RCBS. I've done literally a couple thousand of them. But it it doesn't seem to work like that for everyone. Some dies work ok, some don't. Depends on the particular die.....maybe how smooth it is, maybe one die has a slightly larger radius at the neck/shoulder? Definitely use a burr removal tool on the outside of the casemouth, put a bevel on that edge. I've also used the MachIV trim die which necks to .20 as an intermediate step. The final case comes out slightly longer doing it that way which is good, but I don't bother. Or get a double ended die from Bullberry that'll take it from .22 to .17.
One thing. I clean dies very thoroughly, then use q-tip and apply teflon lube to the whole inside. Then clean that. The inside is slick but not wet.
