Yahrzeit – Jewish commemoration or remembrance of the anniversary of someone’s death.
I think – and please correct me if I’m wrong – that Maori don’t mark a grave until the first yahrzeit. I think – and again please correct me if I mis-think – that is because then you have got through all the other big days when you might feel the absence of someone who has died more strongly – birthdays, Christmas and other anniversaires.
Advertisement

Greek: μνημόσυνον (mnemosynon)
Slavonic: паннихида (panikhída)
I left a hymn from this services on a comment a few days ago
Remembering the departed It is something that seems to have been lost to western culture somewhere along the way – along with much else.
yes, many maori erect the headstone on the first anniversary. although anyone may attend it’s usually a smaller gathering than the tangi and funeral, and a nice opportunity to reaffirm connections with family and friends and to remember the person who has passed away (outside of the shock that follows immediately after they have died).
i dont know if the reason you give above is the reason why, although i am sure it is part of the mix.