It depends. There are some people who bring a lot of value by just being there to answer the occasional questions. When I'm oncall and I know that some colleagu

It depends. There are some people who bring a lot of value by just being there to answer the occasional questions. When I'm oncall and I know that some colleagues are on vacation, I'm definitely more tense. In an ideal world, knowledge would be spread within the team, but with turnover it's hard to reach and maintain that state.