Depends on the type of model it is, a lot of the time. Anime egirl/eboy-styled avatars tend to be some of the worst offenders (often kitbashers who don't know any better), while furry avatars tend to be really well optimized most of the time.

If you aim for medium, that's generally sufficient.

As a note for Jerboa users: the above link may instantly crash the app. At least, it does for me.