[_emacsomancer_]

TeX puts more space after periods/fullstops (which is why you're supposed to do special markup or other measures to mark '.' in the middle of sentences which aren't sentence-enders (e.g. like e.g.)). But it's generally smaller than the equivalent of two manual spaces.

(A nice thing in (La)TeX is that one could follow the "two spaces after a full-stop" rule, which then has the advantage of being an explicit marking for sentence boundaries (which your editor might be able to navigate; Emacs has a convention of assuming two spaces after a sentence-ending '.'), but then the TeX typesetting will take care of making it look right. I lost the habit of actually doing this, for better or worse, except when flycheck/checkdoc/package-linter.el makes me do it for docstrings.)