Superman has been shown in the stories to "know" how fast he is going very precisely, how much something weighs (one of his less "sexy" visual powers that he's used, especially in the Weisenger years, is that he could place small weights and measures in his hand and he knows how much they weigh to the last gram). As I said before, perhaps Superman has a "muscle memory" in regards to using his Heat-Vision; he can guess how hot he's making something, just as some drivers can guess how fast their cars are going, without looking at the speedometer, just by touch alone.
Superman certainly can't wear Clark Kent suits without shredding them, do most feats involving syncing up with microscopic vision, or make a diamond out of coal, without "super fine-grain control" somewhere in the mix.
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