[dagw]

Number and symbols serve a slightly different use. The general rule in English is that footnotes (ie they reference something at the foot of the same page) use symbols and that you only have to use different symbols for different footnotes if you have multiple footnotes on the same page. Numbers are used for references found at the end of the book/chapter/article and have to be unique for the whole book/chapter/articel.

Realistically I've never seen most of those symbols in any book I've ever read. If you're regularly using more than 2 footnotes a page, you're probably better of numbering them and moving the references to the end of the chapter or book.

[Tainnor]

In German academic texts, numbered footnotes are very common. I think it's similar in other continental European traditions. In English texts, I've usually seen more chapter end notes than footnotes.

Also, some citation styles make heavy use of footnotes.