This little gem caught me at a productive moment.
I was going through a school website, and the tab broke. I thought I was going to have to restart IE and lose all my other tabs. Not that big of a deal, but sometimes annoying.
All I had to do was open task manager. And each instance of IE could be shut down.
No more having to restart the whole program losing a bunch of tabs. Treating each instance of IE makes it easier to manage. And improve workflow. You break a page. No problem, just kill that task.