> PM argued: So, you are telling me that we must spend 20% of our time just to k...

> PM argued: So, you are telling me that we must spend 20% of our time just to keep the lights on?

Yes. If the "keeping the lights on" work has been neglected for long enough then yes, in fact 20% is a lowball number.

The context is not so much "keeping the software running" but "reducing the friction in further changes to, and deployments of that software"