I don't remember where, but I read a guideline in one source that said to remove the third consecutive instance of a letter, or to use a hyphen to separate the parts in the case of a compound word, because English doesn't allow three of the same letter in a row. That seems foolish to me, amounting to inferring that such a rule must exist to explain why people rarely encounter such a thing, when in reality one rarely sees it only because it hardly ever comes up.
And, yet, we do clearly apply that rule when we put a verb that ends in "-ee" into the past tense, as in "to tree": "The barking dog treed the cat." I wonder how many people would spell it "treeed".
Yet I would write "brasssmith" for someone who works with brass, just as I write "goldsmith" and "silversmith". Others might write "brass-smith".
For what it's worth, French and Dutch have no such concern: French has "créée" ("created", feminine), and Dutch has numbers like "tweeëntachtig" = "eighty-two" ("two-and-eighty").