Hi @Tracey7
Like @Joan2709 I'm not sure I understand what you mean by rule sets vs custom settings.
When you create a rule in the multi-calendar, there should still be an option to add the trip length to the rule. The multi-calendar has not changed with the May update.
If you're trying to do a quick trip length addition in the regular (vertical) calendar of a listing, then there was a change after the May update. The "add custom trip length" option is no longer in the Availability tab, and Support has confirmed that it wasn't removed by mistake (so it won't be brought back).
To set a custom trip length in the regular calendar now, you have to click the date and change the "minimum nights" on the pop-up screen. This option is only available for nights without rules already applied to them. For nights with rules, you have to add the trip length to the rule since the update.