Different number of chapters in each volume in Special than Adventure

[Alakazam]

I just have a question why there are a different number of chapters in Pocket Monsters Special as opposed to Pokemon Adventures? For example in the first volume of Pocket Monsters Special there are 14 chapters:

1 VS. Mew
2 VS. Machoke
3 VS. Kangaskahn
4 VS. Pikachu
5 VS. Onix
6 VS. Gyarados
7 VS. Rhydon
8 VS. Starmie
9 VS. Fearow
10 VS. Voltorb
11 VS. Electabuzz
12 VS. Snorlax
13 VS. Psyduck
14 VS. Arbok

While in Pokemon Adventures there are 5 parts:

Part 1 - Mysterious Mew
Part 2 - Wanted Pikachu
Part 3 - Starmie Surprise
Part 4 - The Snorlax Stop
Part 5 - The Ghastly Ghosts

Please explain to me why there are a different # of chapters/parts because I don't get it. Did Viz like make up their own parts whenever they pleased? I'm just curious because I'm a newbie to the manga, thanks.

[Purin]

My guess is that Viz combined some of the chapters together to form one with a title and sell them in 5 parts per volume. (Must be a kind of Marketing/Profiteering technique....)
Here where I am the translated manga is sold as a whole book with the chapters/rounds according to the Japanese (and original) version.

[Alakazam]

Well as long as Viz does a good job of not editing too much and basically sticks to the original plot I don't have a problem with their editing. I like their titles better than "VS. *insert Pokemon*" anyway. At least they had to be more creative instead of using the same title over and over again.

[daKING115]

As I read those, I remember each part from the Adventures, so nothing has been edited (the only thing that mite hav is Vs. Voltorb megered with Vs. Electabuzz), so I guess they just divided the chapters differently.

EDIT:
And i see why (i checked my books). Each one of these english u hav listed is three parts, of three different chapters. For Mysterious Mew, it consists of "A glimpse of the glow", "Bulbasaur come home", and "The secret of Kanghaskahn" (Vs. Mew, Vs. Machoke, Vs. Kangaskhan). So each Enlighs book for the first part is three chapters long. :P