For me it was a way to introduce more variety while keeping a core theme. At first I picked my favorite portrait of each HOFer. And, I ended up with several examples of '53 Topps, '33 Goudeys, and T205s - three of my favorite issues. Swapping them out to pick up new types was challenging, fun and educational. I learned of new sets I didn't know existed. The T205s and T206s helped me gain an appreciation for back collectors. I like how type collections represent the changes we've witnessed in the hobby/game of baseball - the variety of products advertised, colors, equipment, technology, photography, etc.
RustyWilly's Portraits - The Types