How come she broke her ankle yesterday in the accident and is just swanning about in a big boot today? I wasn't allowed to put any weight on mine for 6 weeks!
It's rather like when a fight participant is smashed over the head with a champagne bottle. Firstly the bottle shatters into fine crumbs (when it would be unlikely to break at all as it is much stronger than a human skull). Secondly the victim simply shakes his head and carries on fighting (when in fact he'd almost certainly be dead).
When I broke mine four years ago, I wasnt put in plaster but wore a brace on it for six weeks and was told to keep walking as much as I could. And to sit with it raised. Maybe it depends on the severity/complexity of the fracture.