I don't think what you are requesting is necessary at all. The "new" reviews are for the last two weeks only, and it makes sense. Some people aren't on the site all the time or not checking reviews all the time, so it's convenient to check the new reviews to see what popped up in the last 14 days. For any older reviews but still limiting dates fo as not to go back to the beginning of time, simply search reviews and sort by date, then just read back as far as you want, whether it be 1 month, 3 months, 6 months etc. Since that sort feature exists, there is no need to divide up the reviews by time frame.

Now I am surprised you didn't make the suggestion about being able to search rates per time, ad you talked about on the newbie board. That would be a good suggestion, I would be fully on board with.