the cookie cutter thing that was pushed during the 90's is you are supposed to take the whey during the day and casein before bed. this was pushed in bodybuilding magz to sell more supplements of course
the reality is we now know this was a ruse. you don't need protein shakes to build muscle. i've probably had 3 protein shakes in the past 20 years. eat a grassfed steak
Can you? Yes. But I'm not sure why youd want to. Casein is more expensive, takes longer to digest and is harder to mix in a shake. It comes out really thick. Casein is never necessary imo