Fossils T-Shirt

Update: As the Anonymous (silent, kind, resourceful, exquisite, enchanting, gentle) friend remarked, you can also get Animal Fossils by trading in Plant Fossils. So you don't really need so many runs. Thanx for the input, Anonymous <3

I've just run into this guy!! Today - and let me remind you that today is (only) the 15th of September!

This t-shirt, also known as "I Can Hear Only U", is one of the Fossil Event award.

1. In order to get this t-shirt, you need 20 Animal Fossils.
2. Each group gets 1 Animal Fossil from the last boss of each instance.

And now for the maths:

• Assuming that this guy is as lucky as anyone, he will get one Animal Fossil, every six runs. 
• Thus in order to get 20 of those, you need 120 runs. 
• Allowing for Eso, which can be 3maned, we can even be optimistic and deduce that you need 100 runs to gather 20 fossils.

The event has started on September the 7th, ie 8 days ago. Even if we assume that on the 14th, because of the maintenance, you can do the same run twice, it is still difficult to understand..

HOW ON EARTH DID HE MANAGE TO DO 100 INSTANCES IN 8 DAYS??