According to the FIFA Law book, there is no Official requirement for hexagons, which is up to the individual event's committees such as (The World Cup, MLS, Premiere League, Serie A, Bundesleague, etc) as long as the ball meets these requirements:

The ball is:
* spherical
* made of leather or other suitable material
* of a circumference of not more than 70 cm
(28 ins) and not less than 68 cm (27 ins)
* not more than 450 g (16 oz) in weight and
not less than 410 g (14 oz) at the start of the
match
*Is of a pressure equal to 0.6 – 1.1 atmosphere
(600 – 1100 g/cm2) at sea level (8.5 lbs/sq in
15.6 lbs/sq in)

So, since FIFA is above all else in the game of soccer, the correct answer is What is the answer varies by league?