Generally speaking,spelling and grammar have to serve a practical purpose or, as you suggested, rules are abandoned.
The word 'shan't' is unlikely to be confused with any other, similarly spelt word. Whereas, when reading, it's quite useful to be able to differentiate between 'your' and 'you're'. Obviously, when you're speaking, you don't need to pronounce the apostrophe.
(,
Fri 30 Nov 2007, 17:56,
archived)
The word 'shan't' is unlikely to be confused with any other, similarly spelt word. Whereas, when reading, it's quite useful to be able to differentiate between 'your' and 'you're'. Obviously, when you're speaking, you don't need to pronounce the apostrophe.