How long are fifth density cycles?

[octavia]

I was just reading the 2016 Homecoming channeling transcript when I saw that Q'uo mentioned the exact length of a 5th density cycle:

Your illusion is only 75,000 years long, my friends. You may think that is a great span of time compared to the three score and ten that is your lot to exercise, and yet if you look within the fourth density, it is thirty million of your years, the fifth density is fifty million of your years, the sixth, seventy-five million of your years. The density of foreverness has no measure.

So, it would seem that a 5th density cycle lasts 50,000,000 years.