Gaining

Has anybody tried drinking 8000-10.000 calorie shakes 5 times a week over some time?

Hence, gain 3 pounds a day for 5 days over a month? Did you get noticeable results?

How was the transformation in comparison to a gradual one? (for those who have done both)

A long forgotten member named Julia Gulia drank two 5000 calories shakes per day during the week and once on a weekend drank 3 to 4 on both Saturday and Sunday.She was also a very gifted Eater and ate many thousand a day.She once gained 20 plus lbs in a week.This was after having already gotten from 160 to 225 in just a few months.
Another former member Excheerleader drank my 10000 calorie shake over a Saturday and Sunday and gained 8 lbs.Can't recall how many in total she drank but it worked Very Well Check the recipe section for many excellent recipes.
High calorie shakes Always work.The first I heard about them from was Amatrix Cake batter adds a tremendous caloric load for One Dollar so I always recommend that as an ingredient

You'll need to add a fiber supplement like Metamucil to help with digestion. And do your best so the majority of the calories aren't coming from dairy (if you're doing this long term). It's hard on the digestive system after a couple months. Olive oil and peanut butter are just as calorically dense, healthier and much easier to absorb.