Why is it that in the overwhelming majority of games, the 2nd half has much more time added on than the first half? Normally we see for example 1 minute added on in the first half and 4 minutes added on in the 2nd half. How can this be the norm? If the 2nd half added on time is supposed to account for the whole 90 minutes, whats the point of the first half added on time? I just don't get it.