Of course, if the puzzle is something arcane and full of rarely-called letters like FUZZY EARMUFFS or JAZZ FESTIVAL, then ain't nothin' gonna help you.
I disagree; players can help themselves by calling different letters, not falling into the trap of thinking that the point of the bonus round is to call letters that are in the puzzle, studying up on the kind of puzzle that Wheel of Fortune features in the bonus round, using the Used Letter Board, and thinking aloud, those things are all helpful.
It doesn't mean that the day's winner will solve the bonus puzzle every time (it wouldn't be an exciting end to the show if the same thing happened every day) but they'll help. Your second arcane example would start you out with jazz f
ESTiva
L, which is a great head start. Pick letters from the bottom quartile of the frequency chart instead of C-D-M; it will reveal letters in those puzzles that are meant to be head-scratchers.