From about 13-16 my bike was my car and I was always trying to "work" on it despite not having any idea what I was doing. It wasn't until I got back into bikes at 25 that I realized my shifting just got worse and worse because I thought the limit screws served the fine tuning role that barrel adjusters really do. By the time I got a driver's license my 27 speed bike was only working in about 5 gears (all in back, the front was limited to a single chainring). No wonder I gave up riding once I could drive.