Question about automatic seat blocking patterns
 

I don't know if this is something to do with getting pax' weight distributed evenly or something else so I'm asking here.

I understand that an airline would want to block off Emergency row seats, but I'm curious about a pattern I'm seeing on an upcoming Boeing 777-200 flight which is consistent with all the others on this route.

Here it is:

....31 32 33 34
L--.X--0--0--0
K--.X--0--0--0
J--.X--0--X--X

G--.X--0--X--X
E--.X--0--0--0
D--.X--X--X--X

C--.X--0--X--X
B--.X--0--X--X
A--.X--0--X--X
....31 32 33 34

Seats marked X (row 31 GED) don't exist, the others form part of the Emergency Exit row.

We've booked ourselves into row 32 G&E (Bulkhead) but I was wondering why AZ routinely blocks 32D.

Can anyone explain this pattern?

Still hopeful for some points of view on this... anyone?

Quite often the bulkhead rows get blocked out for potential handicapped passengers or for parents travelling with infants that would use the bassinet attachment to the bulkhead.