Do you have a “single point of failure”?

Do you have a “single point of failure” in your software development teams?

A person on the team who is absolutely critical. Irreplaceable.
Only they know how to do something, no one else can do it.
And when they’re not there, the whole systems stops.

1. When one developer goes on vacation, can anyone else take over? Or do you have to wait until that developer returns because no one can work on “his” code? Do developers divide code as “my code”, “your code”, “John’s code”? How strong are the silos? (For example Module A belongs to John, Module B belongs to Mike, and they are the sole owners)

2. When the QA Engineer goes on vacation, does QA testing suddenly stop? Is code shipped to production without adequate testing because “QA” isn’t in the job title of a developer (in the case of fully manual testing, the development team would be forced to undertake repetitive time-consuming QA work or otherwise risk shipping bugs to production)

3. What about when the DevOps Engineer goes on vacation? Does the CI/CD pipeline continue working? What happens when the pipeline breaks – does the team know what to do? What happens when there’s a production bug – does the team know how to access monitoring, logging, etc.?