I will try to answer this question based upon the real-life example – our band clothes selling client, who had been doing SEO the wrong way for many years before he finally realized the website can perform better and contacted us for assistance.
Our client sells 6 types of clothing of 450 rock bands. These 6 types were packed into 3 pages because this is the perfect number to ensure great user experience with the store. For example we placed hats and beanies on one page. Well, we reduced the number of pages but of course not the number of keywords to rank for.