I want to set up a card button that can, among other things, add an increment to the current due date of the card, where different cards have different increments. Common increment values for me would likely be 1, 2, 7, and 30. Hopefully you get the idea.
I expected to be able to use a custom field {{%Date Increment}}, where the Custom Field pop-up would nicely display the increment for me, so I wouldn't accidentally apply it to a card which doesn't have the "Date Increment" variable set. Based on and example in the Trello help on "variables":
when a card is moved to list "Done" by anyone, add member @{{%Tester}} to the card, and post comment "@card Task with priority {{%Priority}} was completed and is ready for testing.",
I expected to be able to say "move the due date by {{%Date Increment}} days", but that doesn't work. Is this another example of Trello catching up with Butler, or is the Custom Field pop-up not as integrated as I understood from the help text, or have I just done it wrong?