Twisting Corridors is not automatically unlocked together with Torghast. To unlock Twisting Corridors, you will need to complete the questline given by Highlord Bolvar Fordragon. This questline starts once you complete the Covenant Campaign quest The Search for Baine.

Can you continue twisting corridors?

If you've completed the last quest for a week as listed, then you'll be able to continue with the next quest after the weekly reset. Note: Twisting Corridors is an account-wide unlock.

How long do twisting corridors take?

As can be expected, the Twisting Corridors are not for the faint of heart or the short of time. At 9.0 gearing levels you can expect to spend 2-3 hours on a full layer clear of 18 floors.