Why drink milk if it's pasteurised? Of course, if you're lactose intolerant, the answer is simple. On the other hand, it's like most things, good if you balance it with the rest of your diet and your training of the moment. I drink it mostly in the morning and I'll eat cheese also at lunch, specially if I train heavy at that moment. If the glycemic index is actually higher than what most thought, then maybe post-workout could be a right time also.