It's padded time imo. Strikes are longer. Something players asked for, more so in the sense of more challenges and raid like encounters, but bullet sponge bosses and enemies add more time and are synonyms to the former in bungie's case. They would rather have people spend 20-30 mins trudging through a strike over players having fun and spending 7 mins in a strike. "What if they get bored after 3 strikes? Well (3)30 min strikes is more time then (3)7 min strikes. That means we can skew the average play time number. It'll look better to the investors."