Dont know about ROTO, but the EBI brands have many, many overseas pieces
i think i was told that the US market fro EBI is that they do releases every 90 days or so
Overseas, its every month (demand from that market)
there is a new EBI product that is all the rage in Japan currently.
im trying to find out what it is

the japan release is called the "Wildcat" and its an HP ball
that would indicate its intended for the rev challenged and/or the patterns over there have some volume

i guess thats possible, i know that EBI does plenty of ball testing here in the states
i would bet other companies do lots of ball testing also.
I would say its more of the business side of things, make something somebody wants and make that transaction profitable(although its most likely small)
but do that every month and now you have something

Supply and demand. They get all of the same releases we do plus several we do not. Many times its just a different color and name and box finish. Others it can be different core/covers combo.

In the end their market has larger sales that support the higher number of releases. Been that way for years.

Just going off of what sunbridge post for Japan.

http://www.sunbridge-group.com/pc/brunswick/ball/index.html