Pair a second engineer with each of the ten largest customer platforms

For several larger customers a single engineer knows how the network and its exceptions are built. If that engineer is ill, on leave, or leaves, others would need days to understand the setup.

Measures

Engineers write the design and the exceptions of a customer in the documentation wiki, and a second engineer joins the on-call rota for each larger customer. The pairing is done for the biggest customers and continues down the list.