Once calories get so high your getting too full during the day you can always throw that shake in in the middle of the night...obviously only if your getting up to pee anyway and not setting an alarm
50 qrams is fine as long as it fits withing your macros like others mentioned.
I used to do 50 grams as well but switched to cottage cheese after just because it was more filling I would wake up too hungry
never tried casein, always heard it was inferior to whey, but only tried whey so cant give opinion on casein, but bedtime seems like it would be best cause slow digesting, but im sure you knew that already