Blood test showed vitamin d deficiency. Why'd dr prescribe 1 pill (50, 000 iu) per week? A smaller dose 7 days a week would be much easier to remember!

That is an option. Vitamin d deficiency has become increasingly common. Taking 10, 000 units of vitamin d every day is a very reasonable approach as well. It is best to take vit d3 rather than vit d2. A cause of low vit d3 is stress induced activation of free intracellular cadmium which breaks down vit d. Doing other things to lower stress and inflammation will improve health as well.