IF I ever take up motorcycle riding again, I'll definitely take a class. I have friends that still ride and from what I've been told, the classes are well worth it.
I recall one year when I put the bike away for the winter, got it out in the spring, took off on a curvy road I liked to push it on, and found that my skills had diminished greatly in just the 4-5 months, and ended up hopping a curb into the grass before I could stop. Fortunately, there was a driveway cut in the curb that I managed to go through, or I'd have lost it.
A good lesson in keeping your skills up. Use it or lose it. Etc.