Cooking and preparing all of that can definitely be helpful. I think you can save quite a bit if you cook and prepare things properly, but I also think about the time involved. Time is a limiting factor a lot but I do think that preparing in bulk and storing the leftovers is a very good strategy (so long as you don't make too much that you can't finish).
That is the scope, never make too you can't finish, time is also something to consider and I mostly for easy meals