Yes, to make sure what I have written makes sense, and to see that it looks alright, and clear up any spelling mistakes (although that doesn't always work).
And if I'm on a mobile device I definitely have to in order to make sure it hasn't auto-corrected words incorrectly, or that my fat fingers haven't just made a mash of letters.
And I always have to have a check on what other people have written if I get a warning that others have posted, since I was banned before for not doing that.