It really is all about balance.
Besides daily attention to the hair, something else is necessary to insure its cleanliness and beauty and the perfect health of the skin of the head from which it springs. For this purpose, the head should be occasionally well washed with soap and water, an abundance of water being used and great care being subsequently taken to thoroughly rinse out the whole of the soap with the water in which the head has been washed.
The water may be either tepid or cold, according to the feelings or habit of the person; and if the head or hair be very scurfy or dirty, or hard water be used, a few grains of soda (not potash or pearlash) may be advantageously added to the water. This will increase its detersive qualities.
After the hair has been washed, which should be done quickly, though thoroughly, it should be freed as much as possible by pressure with the hands and then wiped with a soft, thick towel, which should be done with care, to avoid entangling it. After laying it straight, first with the coarse end of the dressing comb and then with the finer portion, it may be finally dressed.
In ordinary cases once every two or three weeks is often enough to wash the hair and head. The extreme length of ladies’ hair will sometimes render the process of washing it very troublesome and inconvenient. In such cases the patient and assiduous use of a clean, good hairbrush, followed by washing the partings and the crown of the head with soap and water, may be substituted.
This National Post article Maintain your ‘do without shampoo, is about people experimenting with no shampoo over a period of time. People were trying to live without using shampoo for up to six weeks. Some were using home made hair cleansing mixtures such as apple cider vinegar, water and vanilla extract. While many enjoyed their hair’s natural cleansing process, others found that they didn’t like how they looked, smelled and felt.
The occasional washing of the head is absolutely necessary to preserve the health of the scalp and the luxuriance and beauty of the hair when much oil, pomatum or other greasy substance is used in dressing it.
Medical writers have frequently pointed out the ill effects of the free or excessive use of oily or greasy articles for the hair; but their warnings appear to be unheeded by the mass of mankind. Some object to their use altogether. There are, however, exceptions to every rule, and some of these exceptions are noticed elsewhere in this volume. The ill effects referred to chiefly occur from their being used when not required, and in excess, and are aggravated by the neglect of thorough cleanliness.
When it comes down to it, it all has to do with balance.