Become a MacRumors Supporter for $50/year with no ads, ability to filter front page stories, and private forums.
Designed? Yes. Effective? Not always. Rebooting the phone and removing all apps from the recently used apps list are common first steps to terminate abnormal power usage.

And virtually always the problem can actually be traced to one bad app, that needs an update or to be deleted; routinely closing all apps is not necessary and never a good solution for an isolated problem.
 
Register on MacRumors! This sidebar will go away, and you'll see fewer ads.