Remember when she got her head shaved? Is it totally grown back at this point, or is she still wearing a wig? 
I would say it’s grown back, because she shaved her head before I lost my hair to chemo, and mine’s all back.
oh - on her HEAD…
Her hair is quite long, isn’t it? A bit of Googling shows that she shaved it in February 2007, meaning she’s had less than two years to grow it out. My hair grows pretty quickly, and I think even mine has only grown six to seven inches in that space of time. That’s enough hair for a respectably normal hairstyle, but not this much hair.
It’s probably extensions, rather than a wig.
When she’s shown without extensions, it’s a little past her shoulders. I think she puts extensions in most of the time, though, and certainly in her videos.
Lo these many decades ago when I was a young man, I grew my hair that long in one year. It was great, bushy, long red hair. Now, alas, I look like a medieval friar.
Mine would grow about 8 inches in 1 year.
I grew my hair that long in under two years.
Half an inch a month is about normal.