I'll tell you what, right now I am seeing that with WL American V. First time using it and after 8 days it's only down to 1.030 from 1.057. Now it's day 10, still bubbling away. I wish I could see it, I have it in my brewhemoth. I am a bit concerned about it actually.
Normally I brew this ( pale ) with Wyeast am ale II and it finishes in 4 days.