Trello's cards are a great task management tool, but knowing what to do with a card when you're done can be a challenge. This is especially true if a card represents more than one discrete task or has information that might still be useful to someone else.
I just made a small change with how we run the Market Day Iowa Trello. We're leaving cards on the "Done" list until the team can meet in person, something we do a few times a month. The Done list becomes an automatic agenda for reviewing recent progress. We touch on each card quickly then archive it if there's no further business. This process fits nicely with the flow of the rest of the meeting where we already review each in-progress card.
Seems like a simple thing, and it is, but with Trello there's no right way to use it and every team has to figure this stuff out on their own. For a project like Market Day — managed asynchronously with people pitching in when and where they can — it's often the case that "done" tasks still need a last little effort to hand-off information or complete a bit of follow-up.
Going from archiving whenever to archiving at meetings makes it easy for everyone to learn the procedure and ensure nothing falls through the cracks.