Public Restroom Etiquette

I don't know about anyone else, but I appreciate a certain amount of privacy when using the restroom - especially a public restroom. I mean, it's a rather personal part of daily life. If I can, I try to avoid using a stall right next to an already occupied stall, for my own sake as well as out of respect for the unknown bathroom patroness. I believe this should be common restroom etiquette, but I think I may be alone in this opinion..... I entered the restroom at work today slightly ahead of another woman, and she promptly entered the stall adjoining mine, even though there were numerous other empty stalls! Why did she do this?? Obviously, male restrooms pose completely different issues, and I am uninformed to comment on those. But for female restrooms, I think a rule of thumb should be: Allow as much privacy as possible to fellow restroom users, and if possible, do not use adjoining stalls if other options are available.