A certain young player desired to improve his rating so he studied tactics until he puked and played every wild, crazy opening he could buy a book on. He had a measure of success and rose to a little over 1700 and then decided USCF Expert (2000 ELO) was within reach. To reach that goal he decided to do more tactics and buy some more gambit books. I told him I didn’t think that approach would work because he could no longer play in lower rated sections. He had to start playing opponents who would not fall for his cheap tricks and who, generally, knew more about chess than he did. My advice was to study: strategy, endings and play solid main line openings and play over lots and lots of classic games. He promptly informed me that advice was, to use his word, "crap" and he knew what he was doing. I said nothing more.
The result was he lost well over 100 rating points, got frustrated, and quit playing chess. Well, now he’s back. His plan: don't study openings, just tactics. I still haven’t said anything but if it didn’t work before, it won’t work now. In chess, like anything in life, you can’t keep doing the same thing and expect different results.