The following items can all affect the consistency of your drink:
(1) Too much or not enough water being poured into the water reservoir prior to brewing.
(2) The selection of milk ranging from skim to whole.
(3) The amount and strength of the coffee used.
(4) This could also be affected by type of coffee. i.e light roast vs espresso.
It is important to note that each user can customize their latte by making slight adjustments to the ratio of ingredients recommended in the recipe book.