At the level both Sexy Zone and MM'14 are selling, I feel that their weekly #1 streaks are about choosing the right release week, really. Just looking at
the #1 releases so far this year, how many weeks did they each actually stand a chance at #1? So one of the releases might not get pushed back simply because a better window of opportunity might not be there close to the current release date (not that I know who among the big names are releasing what when).