Reducing maintenance effort

You should strive to design simulations that require minimal maintenance. The ideal is to create a simulation whose only maintenance work is proving that it is working correctly when there is a problem in the system of which your simulation is part of. A good way of reducing the proof effort is to have unit tests with good coverage and a developer handbook containing frequently asked questions and troubleshooting sections. Of course, you cannot reach this goal at the beginning, you will get closer to it with every iteration.