It's a great way for skinny runts (like I used to be) to get some extra calories in. Liquid calories are always easier.

Taking that further, though, say... to your situation. I doubt you need an additional 2000 calories in your diet while on the upcoming cycle. Probably 1000 or so would do, and while there's nothing wrong with a glass or two of milk with each meal (which could add 500-1000 cals a day), there's nothing wrong with saving half the jug for the next day.

All that being said, as long as you aren't watching carbs, it's a fast easy way to increase calories for your day. I did GOMAD before it had a name, back in my early teens. Definitely worked for a guy with a runaway metabolism.