Growing space is a nursery's most expensive fixed asset and its least visible one. The heat, the light, the irrigation, the rent and the rates all run whether a bench is full of saleable stock or standing bare. An empty bench is not free; it is a bill with nothing to show for it. A tunnel that sits half-used through the spring is quietly one of the most expensive things on the holding.
The opposite failure costs just as much, only later. Cram a bench past what it can carry and the plants shade each other out, dry unevenly, and grow soft and disease-prone. What looked like efficient use of space turns into a grading-down at the end, or a skip. The margin you thought you saved on space you lose twice over on quality.
Between those two lies the whole discipline: keep the right amount of the right stock on each bench, for the right length of time, and turn it over before it stands idle. That is easy to say and impossible to do when the honest answer to "what is actually on that bench, and until when?" lives only in a grower's head. You cannot plan a space you cannot see the state of.