I don't think that's true. There's 51 volumes of 400-450 pages, or ~23,000 pages. Let's say you can read half a page a minute, or 7.5 pages per day (at 15 minutes of reading per day).
(23,000 pages)/(7.5 pages / day) = ~3,000 days or a bit over 8 years.
(23,000 pages)/(7.5 pages / day) = ~3,000 days or a bit over 8 years.