I have met many people in the last two weeks who say they thrive on a multi-tasking environment and they are able to gear themselves up with changing needs of various kinds of work. I ask them, have you been productive enough? and most of them start to mutter thereon.
People often confuse working on several different things with optimizing their timelines and schedules. Working effectively doesn’t necessarily mean you work on 10 different assignments in the same two hours, but could very well imply working on an assignment for 20 minutes, bringing it to a meaningful close and moving on to another one for the next round of work.
High performance needs a mix of focus and intelligence, not always does divided attention let you achieve that.