The 30-40g of protein absorbtion at any given time is about right. I don't have any "scientific" data on hand to prove this, but the body can only take in so much at once. Anything over 50 is definitely gonna be a waste, and could cause some gastro-intestinal problems
.. Anyways, just spread your intake across the day. Try to take in as much protein as you can from "real" food, and save the mixes for post workout and between meals.