The body will take what it needs and pee the rest out....high dosing is only good for deficiencies but can be toxic if too much is “forced” on the body. A vitamin maintenance program is good only when there are chances that dietary intake will not be enough to maintain average daily dose requirements or the diets in some are quirky(and lacking in some key elements) or appetites are poor.
Stress type elements and vitamins are good for what they are good for, acute illnesses and injuries.
There are no magic potions that will cure everything but even every “Gilead” has its balm!
Be careful with the broad brush statement about vitamins...water soluble vitamins are excreted through the kidneys. However, fat soluble vitamins A, D, E, K and B12 are stored in the liver. Too much of fat soluble vitamins may cause toxicity.