Kanban provides a snapshot of how things really are without trying to assign blame. This provides the opportunity to make genuine improvements, because issues are visible and can be owned by the whole team.

• A card that's stuck on the board for ages is a signal that something is blocking progress or that a task is too big. This is an opportunity to split the job into smaller pieces.
• A column full of cards might indicate that too much work is in progress and that effort needs to be diverted into getting existing work done.

We've had both of these occur recently and we've been able to collaborate on ways to improve the situation in both cases.

In the first case, we've organised to get together as soon as it's apparent a card is more work than expected, to see if it can be broken up, or slimmed down to provide essential value.

In the second case, we simply stopped picking up new work and helped verify acceptance of the existing work (things had piled up in the signoff column, since we'd had some rather large cards messing up our flow).

In both cases, the underlying cause would appear to be cards that are too much work. This presents a further opportunity to make improvements in breaking up cards into similar sizes, on which we can focus in the future.