First, keep in mind the important difference between considering any advice on nutrition and following rules (see video at 5.4).
Second, please take my answer in the context of: “this is what I do, for myself, based on what I believe”. I do eat protein at every meal, but I think the quality of the protein is the top factor to consider. I don’t buy meat from supermarkets and rarely in restaurants – even in the good old days when I might go to one! I eat the best quality I can find: grass-fed, raised as naturally as possible.
I understand that protein becomes more important with age, so the older you are the more you may need to maintain lean mass.
Having said that, I rarely eat breakfast – so no protein there!