I've spent a lot more time on Native than Napoleonic Wars, so I don't know how I'll sound when I say that I think spamming can be a valid tactic.... sometimes.
For example, if I'm fighting someone and I realize that they feint a lot then my plan would most likely be to spam them. For me the trick is moderation. If it looks like I can pull it off, then I go for it, and stab twice.
But I never, ever expect spamming to work on everyone, or for it to work all the time. It doesn't.