Here at Gun Nuts we’re big advocates of getting professional training. One of the big reasons I push that people get training is because it’s difficult for self-taught practitioners of anything to identify places where they’re making mistakes. Video taping yourself practicing can help, but it’s always useful to have a second set of eyes watching what you do and making corrections or offering tips.
However, just taking a class doesn’t necessarily mean you’re going to get any better at what you do. This can be for a number of reasons: the instructor isn’t very talented, the class is way below your current skill level, etc. However, assume for the sake of argument that the class is appropriate for your level of skill and that the instructor is talented enough to actually provide useful feedback to you as a shooter. It still doesn’t guarantee you’ll get better.
The reason it doesn’t guarantee improvement is because improvement is self-motivated. You can take 5-10 training classes and if you don’t take any of that learning and practice it in your own time, you’ll never improve. The cycle of improvement looks like this: