By the actual calculate :

first six hour = 100% - 14% = 86%
second six hour = 73.96%
third six hour = 63.60%
full one day = 54.70%

You can see that just one day and the price should drop near 50% already if it drop every 6 hours? so I guess miss translation? or it is either game day/ earth day misconception?

They mean 90 days of in-game time that the price will drop below 50% ?