its worse than that
specifically the fin design; flat, slit, louvered, corrugated, dimpled. etc
lots of fin designs out there, now compound that with the possible fin thicknesses
and there is yet more of which I will not speak

but yes, this is addressed through parametric modeling (testing) and analysis

while there are numerous 'solutions' to a given task, I have found that very small changes in the wrong area have disproportionate decreases in performance
- if an item (liquid/air heat exchanger) is to excel, it must be close to spot on in the tube/fin area