Whey is great for post workout because it breaks down and gets absorbed in one’s body fast. Casein is a good choice to take around the evening or before bed. It lasts longer in your body because it gets digested slower.
Personally, I do use whey post workout but I like to eat. A better choice then casein at night is a bowl of cottage cheese. Remember, protein shakes are just a “supplement” to support your nutrition and boost your daily protein intake. You’re better you getting your protein from food throughout the day.