Every women becomes Rajaswala and in that time period, there are some rules in Hinduism to follow.
According to scriptures,
Is the time period fixed for all women?
Vary from 3 days to (approximately) a week based on the women?
Yes, it is fixed at 3 days. It does not vary under any circumstances. The 4th day is the day to take bath and from the 5th day on wards religious activities etc. can be resumed. This is what is mentioned in the Smriti scriptures.
If discharge continues to happen even after the period (of 3 days) is over, then that does not create any impurity.
This will be clear from the following verses:
A woman in her monthly courses, is restored to purity after having washed herself, on the fourth day. When the courses actually cease, however, it is then that she should engage herself in the performance of the rites due to the manes and the gods.
When the menstrual fluid flows from day to day on account of a disease, it causes no impurity; that is, uncleanness by reason of disease alone.
Parashara Smriti, Chapter 7.