No man.... You can't count it that way
Two months are 60 days, reading half an hour per day. So they expect the Kindle to last 30 hours in active use, light on 10, no data connections, and IIRC, refresh on 6 pages. The numbers of hours the Kindle lasts will not be less when you read more, they'll just be used up earlier.
They will be less if you turn the light up to 24, engage all data connections and set the refresh rate to one page. You might actually drop to 15 hours or less, I think. With the light off, wifi off and refreshing each 6 pages, you should easily hit the stated 30 hours of usage, probably more.