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Of course, it doesn't really matter for the overall experience, but aren't you exaggerating with the "unfamiliar for non-online players"? Who is bothered by a separate tab when launching the game with timer settings? How does this clutter the functionality?
And move the manual timer setting somewhere deep within the custom options.
We don't plan to completely remove the existing options – who knows, someone might want monsters to be strong or water to be none, or a non-standard number of opponents.
But since all of this is non-standard, it's not necessary to put it in a prominent place.