Gaining

Your point on whether to drink a whole bunch at once or spread them out by having one a night over a longer period. I would go with one a night. Consistently adding extra calories is a sure way to gain, though slowly, but with consistent results.

Sexiest gains are over time. My gf had puberty and her first pregnancy basically back to back, then it stuck around.

I think there's a lot of wisdom to what everyone above has said about spacing it out and not eating more calories than your body can consume.

However...

The times when I've eaten the most obscene amount of calories are the times I've seen the biggest gains. Part of this is because I have such a slow metabolism, I think, that I digest slower and absorb more calories than a lot of people.

It's natural for me to try and rush my gains, too! I understand the intense internal pressure that comes about once you decide you want to get substantially fatter than you are. But one thing I agree with unequivocally is that you shouldn't eat to the point of being sick or feeling ill. Calorie absorption aside, doing this caused eating to feel like an unpleasant chore, and I had to recalibrate my relationship with food just to like it again.

If you gain weight relatively easily, what I suggest is trying is to drink as many drinks as you can enjoy having in one night. Then wait a couple days and keep a close eye on your weight. If you shoot up a handful of pounds, you might be like me and benefit from "the more the merrier" calorie approach!

Just an FYI, the shake I was drinking was a 10,000 calorie combination of 2 quarts of heavy cream and a box of brownie mix. I'm sure I didn't absorb every last bit, but I'll be damned if I didn't literally wake up fatter the next day For some of us, weight gain just works that way! Good luck and happy fattening