It depends on the circumstances. Often a meeting will have multiple topics, and different people can be more or less engaged at different times. And often it'

It depends on the circumstances. Often a meeting will have multiple topics, and different people can be more or less engaged at different times. And often it's useful to have somebody around to answer questions if anybody comes up, but she or he isn't needed for most stuff being covered. In both of these cases multi-tasking can be very efficient. Of course as you say it can also be abused ...