[jedberg]

It depends on the role. I've always worked in sysadmin/devops, so a lot of programming is under duress of an outage. Even for the "regular engineers", I need to know that they can fix a production bug in real time, or at least figure out what to roll back.

And even for the non-duress situation, there are plenty of situations during normal work where a senior engineer will have to jump in and contribute to a problem they've never seen before.