If you have 20M lines of code you hopefully have more than 1 team and you also hopefully have more than one service w/ the right interfaces/apis between them.

If you have 20M lines of code you hopefully have more than 1 team and you also hopefully have more than one service w/ the right interfaces/apis between them. As unrealistic as it sound, yes, if you're oncall you need to be able to understand the problem and fix it/mitigate it at 3am. This opens another can of worms around what is worth of a 3am page and how development, deployment and monitoring should be done but if you wake me up I should be empowered to do something about it