Three glasses of milk equals 90% of daily requirement. How many glasses you need depends on how much calcium you get from other foods.
You can drink 20 glasses of milk, I don’t give a damn. I am just saying that if you need calcium, there are other (better) sources than gulping on 3 glasses of milk.
In the calcium you get is directly related to the amount of magnesium in your system, if you have a lack of magnesium you cannot absorb the calcium.