You can though. Most of the labor is in skills that are easy to teach. You can take your half your seconds and promote to foremen, the other half as seconds under the old seconds. The foremen get the old third line as seconds, and you hire all new third-line people. There are a few people who aren't worthy of, or don't want that promotion, but overall the limit is how fast you can convince inexperienced people to work for you. This process can repeat yearly. You can also work more overtime - money talks to a lot of young people.
You do take a small productivity hit, so it isn't all smooth. Still there is plenty of opportunity to expand to meet demand.
