While we might be good multi-taskers this does not mean the multiple tasks will be exceptionally performed. Further, it means we are diluting our energy as well as our effectiveness.
So often people get obsessed with managing time. By this they mean getting as much done in the time they have. This is wrong-headed. We should instead be focused on managing energy toward performing better work not more.
Our goal should be to do the BEST work in the time we have allotted.
Think of tasks the way a sprinter things of theirs. They see the finish line. They go all out a the their highest level full of focus and energy. Tasks should be sprints NOT marathons.