Women usually take longer than a week to normalize for shampoo because they do do much stuff to their hair with chemicals and stuff. Normalization is a real thing that does happen, and has nothing to do with getting used to stuff you normally find objectionable. It's all about the natural oils in your hair. Standard shampoo strips it with industrial cleaners. Your body works extra to replace it.

Many find that scalp and hair issues go down considerably without shampoo. Although I'm a guy with short hair, I am among those. I do use a Thai deodorant stone, which seems like it will last forever. it doesn't cake up or steak or anything. I might try going without some day. I think one's diet has something to do with how easy this is to do. I don't think I would be as successful if I ate like I used to.

Here's a blog about another guy who do it and received a lot of attention:
http://freetheanimal.com/2010/12/a-m...mpoo-free.html