MRPs shouldnt be used post workout IMO since they are usually a blend of proteins thus absorbed too slowly + the maority dont have enough carbs in them
I use MRPs sometimes when
a) I'm away and need to have something handy to use
b) At the office when i dont have time to make something for my 11o'clock feed lol
c) Second Post Workout if im too tired
Sometimes i have one pre bedtime too but i think i go through on average 3 mrp sachets a week so i wouldnt say my diet depends on them