Erhm....since there are 10 contestants, and only 3 will get through, it is obvious you need to have the top 4 to keep everyone in suspense. Coz to select only 3 out of 10, you know that the first buch 1 - 5, will probably miss out....and everyone will probably expect it. And of cours,e you have to leave the last spot between 2 people......so it's down to 2 spots between 8 people......so when you get your name read out and everything, you probalby know you're gonna miss out....
It is too complicated to explain. but i hope you understand what I meant!!