One thing that should be mentioned is that one of the easier ways to avoid interruptions is to simply say "No" more often. As it goes with most simple advice, i

One thing that should be mentioned is that one of the easier ways to avoid interruptions is to simply say "No" more often. As it goes with most simple advice, it's much easier said than done, but delegating tasks better is one skill as a manager that I think must be learned and practiced over time than something that is innate to people in any way. Unfortunately, it's extremely hard to stop the habits of a bunch of people unless you actually change things enough around them to encourage change. Becoming a single point of failure as a human resource is no different of a problem to me than neglecting to design your systems for high availability, failover, and sufficient redundancy. Bus factor is something that does matter but people seem to only realize these things are so terrible in hindsight of a disaster. Unfortunately, I've found that most organizations being reactive by nature rather than proactive tend to require disasters in order to have a sufficient shock to their workflows and methodologies.