Matthias Hohner nailed it over a century ago! There are a lot of things about the Marine Band 1896 that are perfect by design. Admittedly, mass-production takes its toll and not every one made is perfect.
But all the details he settled on seem to be bang-on.
I get asked about the perfect comb thickness a lot. I offer regular, thin and thick combs. Each has its own strong points and weak points. The thinner the comb, the better the response but at some point the tone will sound "thin".
Thick combs can offer deeper tone, but responsiveness suffers and a thick comb can make the harp feel sluggish.
The good news is that you can get pretty much the best of both worlds without having to make a huge trade-off.
The thickness of the stock Marine Band comb is right in the middle of both these features.
Here's a representation of these effects. This is not an evidence-based representation, rather a subjective display of what I have observed about the effect that comb thickness has on the instrument.
The thinner the comb, the better the response:
The thicker the comb, the deeper the tone:
Put the two graphs together and you see there is a nice range centered at 5.8mm where both features are available at the same time: