I had to stop doing this because the den became way too large. There are a few soaps and aftershave I will continue to match because I really like them but I have started using unscented soaps or soaps that do not have a strong distinguishing scent such as Sterling Unscented with Beeswax, MWF, Cella, etc. When I hit roughly 40 pairings was when I realized it was out of control, LOL.
I usually combine whatever I feel like using. My usual AS is Clubman Special Reserve, but I recently picked up a bottle each of Proraso Red and Green. It would be too easy to combine the Proraso Green cream with the Green sauce, so I usually don't do that -- but I could, and I bet it would feel and smell great.
I try to match the overall scent profile...aquatic with aquatic...citrus with citrus...Bay Rum with Bay Rum...Barbershop with Barbershop...spice with spice. Although sometimes...I just pair by what my olfactory senses are telling me would be a good match.