What do you do to keep your Coding Interview skills sharp?

After realizing that even as a moderately competent junior-mid-level developer my fitness for interview problems drops drastically as soon as I'm employed.

Studying algorithms reminds me of my most hated classes in college, mostly because my professor had no interest in teaching and was really only there for his research...

However, I still have no clue how to keep my interview-foo top notch while not freaking out about trying to get a job as well. I still can't believe friends of mine can line up 5-7 interviews in the course of a week and then get offers from 60% of them on their first try.

Oh incidentally I learned recently that things you learn in the last 90 minutes or so before going to sleep are less likely to be retained.

I believe I read this in "The Expert's Guide to Sleeping Well" by Chris Idzikowski, which is a well-researched book... but I didn't take any notes on where in particular I read it.

It was a striking result because a lot of research shows that sleeping after studying is crucial to consolidate the learning -- this added the nuance that a gap between the study and the sleep is also needed.

Actually do interviews. After 20 you'll see what you should actually focus on, as opposed to cookie cutter problems that test memory vs. in-moment applications.