I've made this several times now. I buy the can of five biscuits instead of eight and cut them smaller. Holly says in the comments that each chicken breast should be ~6oz — 1.5lbs of chicken total — so it's usually just two big cuts instead of four for me. I also don't bother defrosting the veggies anymore, and I use the bags that include corn.
Edit: I increase the servings from 4 to 6. I use cream of chicken, celery, and cream of mushroom, and I think the last is very important in making it more savory because for some reason sometimes the dinner has a sweetness to it that I don't like.
