Why aren't the functions in sequntial order? I am an IEI, so why do I write them like the left colum and not the right?

[|]..........[|]
[|]..........[|]
[|]..........[|]
[|]..........[|]

or with the fuction numbers:

[ 1 | 2 ].........[ 1 | 2 ]
[ 4 | 3 ].........[ 3 | 4 ]
[ 6 | 5 ].........[ 5 | 6 ]
[ 7 | 8 ].........[ 7 | 8 ]

is it just because they wanted a checker board?