How much blood can a person donate at most a year? Is it good for people's blood circulation to bleed more?

The total blood volume of healthy people accounts for about 8% of body weight, and that of adults is about 4000 ~ 5000 ml. Usually, 80% blood circulates in the heart and blood vessels to maintain normal physiological functions; Another 20% of the blood is stored in the liver, spleen and other organs. Once blood loss or strenuous exercise occurs, blood will enter the blood circulation system. A person donating 200 ~ 400 ml of blood at a time only accounts for 5% ~ 10% of the total blood volume, and the blood stored after blood donation will be replenished immediately without reducing the circulating blood volume. Water and inorganic substances lost after blood donation will be replenished within 1 ~ 2 hours; Plasma protein, synthesized by liver, can be supplemented in a day or two; Platelets, white blood cells and red blood cells also quickly recovered to their original levels. The blood of human body is constantly metabolized. Many blood cells are aging and dying all the time, and at the same time, a large number of new cells are generated to maintain the balance of human metabolism. After blood donation, due to the enhancement of hematopoietic function, the lost blood cells were quickly replenished. Therefore, a healthy person who donates blood according to the regulations will not have any influence on his body, let alone "hurt his vitality", but will be beneficial to his body.