Does updating Custom ROM require a factory reset ?

Hi I currently use the custom ROM Renovate 2.1, and want to update to 3.0, which was just released on 22nd July.

So if I just want to update a custom ROM, do I still have to backup all apps with Titanium Backup, and do a factory reset with TWRP before flashing the updated custom ROM? Or can I skip these steps?

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