For a lot of us, it ends up being trial and error process to figure out the fins for a new board- as this thread shows. Can be frustrating, expensive, as well as surfing time-wasting (which is the worst). I'm about 3 years into really experimenting with fins and trying to figure out what works for me & the boards I ride. But there are so many variables in board design and conditions for each session, trying to isolate what worked when a turn/wave/session felt good is just a guess. I'm honestly not sure how much more I really know than when I started!
Also, complicating matters, flex patterns vary from fin to fin.
One thing I've noticed is fin area seems to be an irrelevant component for the most part as templates, thickness, and flex patterns vary.
A larger fin can feel loose and lack drive while a significantly smaller fin can feel drivey and tracky.