Turning off the phone is useful if you are low on power and don't have a way to charge. I do this sometimes when traveling or in the city.
When I go through open apps, it is usually to get back to something I was doing, rather than to clear it. Finding what you were just looking at 2 seconds ago shouldn't be considered a power user feature.
When I go through open apps, it is usually to get back to something I was doing, rather than to clear it. Finding what you were just looking at 2 seconds ago shouldn't be considered a power user feature.