All production points would have a reliability value and an adjustable maintenance schedule. The more often the production point gets maintenance, the more reliable it is, the less maintenance it gets, the less reliable.
Here are the trade offs: Scheduled maintenance takes a fixed amount of time, say 3 minutes. The reliability operates on: After every process there is an increasing chance of a failure, maintenance reduces this back to zero. If there is a production unit failure, that production station has to be repaired and is stopped for a random amount of time (2-15 minutes).
Technology improvements reduces the chances the cumulative chance of failure for each process, so less maintenance is required.
That means you also need a maintenance staff that is deployed for scheduled maintenance and repairs.