It does depend on the individual, and by that I mean, if I was 10 kgs overweight, then 1 kg a week is probably unrealistic. When I was over 180kgs, I would have been really pissed off if I was putting in all that effort and only losing 1 kg a week. Now that I am around the 100kg mark, I still expect to lose around 1 kg per week, but my body has other ideas, no matter how much effort I exert.
What I'm trying to say is that it's all relative. At a much larger weight, 1 kg per week is not only possible, I think it's expected. The closer you are to goal, the less likely it is that you would be able to achieve such results.
I still find it interesting that many people are banded at a weight a lot less than I am now (and I feel like I'm almost there). Once again, I guess it's all relative.