The stuff on your resumé should speak for itself. If you feel the need to go on about something that’s there… make sure you’re telling us something we couldn’t have gotten from the resume itself.
OF COURSE you should dig deep into your ace in the hole job that accounts for the bulk of your career, and get into all sorts of detail and play-by-play. But never, ever JUST tell us THAT you accomplished X and worked at Y, and earned an award in Z… if we could have just as easily seen those things in bulletpoint.
This happens a lot, and it almost draws attention to the fact that the writer ISN’T writing about something else. Result: it forces the reader to wonder, “Is this all this kid’s got?” and suddenly what COULD have been a standalone bulletpoint, that had been impressive, now becomes a red flag.