I find it's a mix of both. Most people don't have the luxury to learn for a year. They usually have learn on a job. My first two years of working was doing underpaid grunt work, but it was in the direction I wanted to go. Even though it paid poorly, it got me there.

Another risk with learning on your own is that it's still mostly unguided. Because you're not being paid, you can often go down an idealistic path that doesn't work in the real world.

Also even if you do have a year, be careful. It could take a few months to get a job, as the interviewing can be tough.