Trello – Moving cards between boards

I agree with your friend about not dividing up into separate boards by type of job.

With your examples such as 'Design ideas' etc, I think they really do fit naturally within different lists on the same Board. It's exactly the sort of usage that Joel demoed in multiple videos about Trello.

The only thing I can think of, to help manage very long lists, is to use Trello's Labels system to put categories on cards, and then use filtering. You should definitely give meaningful names to the default labels.

I wrote up some tips on how to use labels recently.

Having said that, fairly early on the Trello on Trello board got huge, and eventually they reduced the scope of it. So it's does seem to be a well-known problem.

There isn't a way to collapse boards together.

There have been a lot of requests for a view that combines all your cards across all boards. There is a card for it here: https://trello.com/c/UOIrt48P