You should take classes if you want to produce great knitting.
I often have students tell me how sorry they were they didn't take classes sooner once I teach them a technique they haven't seen before. I still take classes and I've been knitting longer than I like to admit.
Often we learn to knit from a friend or relative who has basic skills and we don't realize that there are many other techniques to choose from. The more techniques you know the more solutions you have to your knitting problems.
My unscientific polls of students have told me that only 20% of you feel comfortable learning new techniques from books or Internet sites. You say you need the feedback of an observer to correct problems that you can't see for yourself while in learning mode. Another 20% tell me they have no problems ever getting gauge. That means 80% of you don't get gauge so you need strategies on how to fix that problem if you want to knit from patterns and get great results.
That's why you need to take classes. So please support your LYS and the design community who wants you to be a great Knitter.