By now, most people who read this know that multitasking causes a lot of problems in organizations. It creates delays, lowers quality, and creates more and more tension in an organization.
A recent HBR Ideacast with Mark Mortensen described a variant that I have talked about but had never named: "multiteaming" - being assigned to multiple (different) projects. The aspect that the conversation brought about is the issue of the natural induced work of being on any team. If I'm sitting in team meetings, there is a natural tendency for additional work to get created as the effort moves along. Work gets induced. And when I'm doing this across several teams, this can get very messy for people. Priorities are pulled in many directions. People become very busy. They are multitasking, and yet no one can see it because this induced work is largely invisible to the organization.
The worst part of this is that people often pull in the people who have expertise or knowledge that every team or project needs. They are at 10% on 15 projects and every project needs them at for the same two or three days of the month. We waste the experts time and capacity by doing this to them. (We waste everyone else's capacity too.)
The general direction here is to find ways to reduce multitasking. There are many ways to go about it from Kanban-style boards to enforcing full kit to Critical Chain Project Management and others. But to start: ask people how much they have on their plate. And emphasize finishing over starting.