Thanks, David.

"But she didn't snarl with rage as she usually did." "...as usual" is more correct, or at least it used to be so. Then "as she usually did" makes it clear. I remember during the 1960s criticism of the advertising slogan, "Winston tastes good like a cigarette should" and my English teachers pointed out that it should have been "...tastes good AS a cigarette should", but by that time the slogan with incorrect grammar had already taken hold and convinced millions of paying customers.