Real experiments can take days to run, but many variables can be tried in a few minutes using computer simulation. Optimization with models and real time dynamic control is in its early infancy; however, bases for such work are advancing steadily. The foundations for all such studies are accurate material balances.
Simulation pays off. One of my students, Thomas Young, joined Squibb in about 1970 and soon made major improvements in the yields of two different antibiotic fermentations, mostly as the result of simulation. A vice-president at Squibb told me that Tom was just about the best person that they ever hired and that his development research saved their company many millions of dollars. It was partly the ability to test ideas on the computer that led to rapid progress, but even more important was the thought process. Deriving equations for simulation forces you to think deeply and analytically, and many new insights arise.