Let's assume that I have a kanban board that has a "Test" column with a WIP limit of x. In the general case, I should not add a card to this column until there is a free space -- at least one card has moved to "Done". Instead, I should give as much help to whomever so that the card currently there can be progressed so they move onwards.
Now, in our case, we have to wait for hardware so no matter how many bodies, as long as the hardware is not ready, we cannot progress this. The way we deal with this is to have a limitless WIP swim lane that hold such stalled cards.
Is this reasonable? Is there a better way?