X-post with peggy there. Yes, if we were having steak or something, then the portion size would probably be bigger, but then I would have less meat later in the week. But generally I tend to aim for half the plate being veg, just over a quarter being starchy thing and under a quarter meat. With something like stew, there'd be less meat, with steak there'd be more, but I wouldn't eat steak every day.
And yes, I have magical chickens too...would aim to get 4 meals out of the 1.6kg roast chicken we had tonight (roast, stirfry, risotto and either wraps or soup with the scraps).
Mind you, I had a colon cancer scare last year which really made me look at my diet and how much meat I ate, and have been actively trying to increase the veg content and reduce the meat content of meals (which has been hard, as there were loads of veg I didn't like...turns out, yep, didn't like them when I was 8, do like them now).