Riding RAGBRAI all those years has made me a much better biker. I would never have thought I could have a couple of beers and ride before first riding RAGBRAI 20-some years ago. But due to riding with a group, riding in driving rain and on wet and even flooded pavement, I learned a lot about what makes you safer on the bike. I can now easily ride a mile or more on the painted edge line without swerving off of it to either side for even a moment, even when working hard on a moderate climb. Learning to bike straight rather than slightly swerving side to side is a must if you are riding for miles in a group or on crowded roads.
That's not to say that I haven't gotten on a bike a time or two when I probably had no business being on it, but that's another story.