Is it necessary to sit when performing ghusl for menstruation or ritual impurity to ensure water reaches all parts of the body?

The obligatory aspect of ghusl (ritual bath) after major ritual impurity (janabah) is to ensure water covers the entire body, including hair and skin, based on the hadith of Aisha (may Allah be pleased with her) and the hadith of the Prophet (peace be upon him). Jurists have concluded that it is obligatory to make water reach every external part of the body. If water does not reach certain areas, such as between the buttocks or a woman's private parts, except by sitting down or rubbing, then it is obligatory to do so. However, if one presumes that water will reach these areas without sitting down or rubbing, then it is not obligatory to do so.