[darkwater]

I think I didn't explain myself very well: clearly on-duty must sleep if it's a multi-day incident, but they also need extra help when they are awake! If the business is completely down, there isn't normal work to do for other engineers so, even if they are out of their typical domain, they might give good insights, novel ideas or fix some side issues that will help the ones with more domain knowledge.

[acranox]

The problem is that you don’t know how long the outage will be when it starts. I once saw a large outage start, everyone jumped on to troubleshoot, thinking it would be an hour. 8 hours later it’s still an outage, and everyone is still on and burned out. Management should have told half the people who jumped on at the start to go away and be prepared for a phone call in 8 hours to provide relief.