Although a single drop of 2 M HCl reduces the pH of 100 mL of water by 4 pH units (from 7 to 3), there is no change in the pH of the buffer when a drop of 2 M HCl is added to 100 mL of this buffer solution. Thus, the pH of the buffer solution is truly buffered against the effect of small amounts of acid or base.
How long babies nurse also depends on their age. As babies get older, they become more efficient, so they may take about 5-10 minutes on each side, whereas newborns may feed for up to 20 minutes on each breast.
Depending on your nursing habits, it takes anywhere from a few days to a few months for milk to dry up. The length of time it takes for breast milk to dry up after weaning a baby varies from woman to woman. For some women who have nursed regularly for a long period of time, this process takes weeks or even months.