It depends how many buttons you have. You'd always need to check you reach the count -1.

What I mean is that if you only have two buttons, yes, checking one will do. If it's false, the other must be true.

If you have three, though, you'd need to check at least two. If 1 & 2 are false, 3 must be true. For 4, check 3, etc..

Does that make sense?