Yes I made up the word 'checkedy' but so what, you should see some of the howlers I've encountered in my time. One of the best would be an applicant applying to a mechanical engineering role who misspelled mechanical!
You really can never check your document too many times, well you can actually, if you do it too many times you'll probably overlook some errors so it's best to get at least one other person, better two, to have a look over it as well. They don't have to understand it, just look for grammatical and spelling errors, you've no idea how off putting it is to a recruiter when a candidate clearly hasn't been bothered to take the time to make sure all is right, it's likely to mean your document ends up in the B file (bin) so don't take the chance and checkedy check check!
Have a look at these links for some facepalm worthy mistakes.
This is my favorite, an infographic from @socialtalent