Theme-Based Vocabulary Building

As I argued in “How far could we apply Content-Based Instruction?” Theme-Based Language Instruction, the sub-method of Content-Based Instruction, is naturally associated with cramming for entrance examinations. The first publication of “Janru Betsu Eibun Dokkai Izen” (Furufuji Akira, Kenkyu-sha) in 1992, the first Theme-Based cramming reader, suggests having secure background knowledge in related themes or genres has become essential to understand English essays within limited time in today's English entrance examinations.
Since then, varieties of Theme-Based cramming vocabulary textbooks have also been published, such as “Ei-tango Bun'ya-betsu” (Kanai Takahisa et al, 1996, Kawai Shuppan), “Wadai-betsu Ei-tango --- Lingua-Metallica” (Nakazawa Yukio, 2006, Z-KAI), “Sokudoku Ei-tango” (Hayami Hiroshi, 1992, Z-KAI), “Dokkai Ei-tango” (Kohbe Fumiaki, 2003, Gakushuh Kenkyuh-sha), and as such. At first, all we had to do seemed to be choosing the right one at the right time.
As a part of their title, “-betsu” (namely: “classified”), suggests, the first 2 vocabularies are divided into sections of themes. The latter 2 have either “doku” or “dokkai” in their titles, which suggests they incline to reading, although their words and phrases are slightly divided under certain numbers of themes.
Some English teachers firmly believe that "words should be taught in the context of story, theme, or content area." (Barney, p.3) Because of the belief, the latter 3 titles have short essays to give their words and phrases certain contexts.
Sharing the belief somewhat however, I find the 3 rather reading-oriented and, above all, high-class-entrance-examination-oriented. Simpler structure may be preferable.
Then should we choose “Ei-tango Bun'ya-betsu”? Unluckily enough, it is out of print. I am afraid we have no other way but to make it by ourselves.
“Ei-tango Bun'ya-betsu” has 2178 words and phrases. I have entered the English words and phrases into an EXCEL file. Those words and phrases are divided into 15 categories. The categories have 83 sub-categories in total. The category names and those of sub-categories in the title are in Japanese. I have input the data along with their English translations. The question is whether its grouping is appropriate in quality and in quantity or not.
The number of sub-categories, 83, means each sub-category has 26.2 words and phrases on average. The biggest number of entries is, however, 59. From my experience, students might find difficulty in handling, mainly in memorizing, new words and phrases when the number gets far beyond about 20.
Reconsidering the categorization of the data might be indispensable. Including and excluding some entries may be inevitable. Checking my translation of category and sub-category names must be critical.


References:
Carol Barney, "The Impact of Contextual Vocabulary Strategies for ELL Learners", 2005, Shawnee Mission Northwest High School, http://www.smsd.org/custom/curriculum/ActionResearch2005/Barney.pdf
Jack c. Richard and Theodore s. Rodgers, "Approaches and Methods in Language Teaching" (2nd ed.), 2001, Cambridge University Press, New York
Eiji Leland Suenaga, 'A Content-Based Approach to the Learning of Vocabulary Through Composition and Schematic Mapping', "Sｔudies in Culture" No.1, November 1993, Hkkai=Gakuen University