While I don't read scientific literature that much, I do make formal predictions pretty often. Typically any time I notice something I'm interested in that will be easy to check in the future.

Will I get to bed on time today? Will I be early for the meeting tomorrow? Etc.

I second the anecdotal evidence that this is a "live" exercise. Sidenote: it took me way too long to realize I needed to write all my predictions down. I spent a few weeks thinking I was completely excellent at predicting things.