I am currently taking 7000 UI daily, because medic told me to do so, thing is... even the same medic, sometimes told me to take another dose, because he forgot I was already taking it, when I told him what I was taking, his reply was... "huh... that I think is about right".
My experience with other medics weren't better.
Also some were AGAINST me taking Vitamin D, because 7000 UI is viewed by many medics as toxic, but I have hypothyroidism, and one of its issues is that some people show vitamin D deficiency symptons even with correct blood serum levels (and the symptons go away only after forcing the levels go higher than normal), telling that to medics also resulted in mixed results, some said they would read more, some got mad at me, some agreed with me.